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[sahyn-in] /ˈsaɪnˌɪn/
an act, an instance, or a time of signing in.
Origin of sign-in
First recorded in 1945-50; noun use of verb phrase sign in


[sahyn] /saɪn/
a token; indication.
any object, action, event, pattern, etc., that conveys a meaning.
a conventional or arbitrary mark, figure, or symbol used as an abbreviation for the word or words it represents.
a motion or gesture used to express or convey an idea, command, decision, etc.:
Her nod was a sign that it was time to leave.
a notice, bearing a name, direction, warning, or advertisement, that is displayed or posted for public view:
a traffic sign; a store sign.
a trace; vestige:
There wasn't a sign of them.
an arbitrary or conventional symbol used in musical notation to indicate tonality, tempo, etc.
Medicine/Medical. the objective indications of a disease.
any meaningful gestural unit belonging to a sign language.
an omen; portent:
a sign of approaching decadence.
sign language (def 1).
Usually, signs. traces, as footprints, of a wild animal.
  1. a plus sign or minus sign used as a symbol for indicating addition or subtraction.
  2. a plus sign or minus sign used as a symbol for indicating the positive or negative value of a quantity, as an integer.
  3. multiplication sign.
  4. division sign.
  5. a symbol, as or !, used to indicate a radical or factorial operation.
verb (used with object)
to affix a signature to:
to sign a letter.
to write as a signature:
to sign one's name.
to engage by written agreement:
to sign a new player.
to mark with a sign, especially the sign of the cross.
to communicate by means of a sign; signal:
He signed his wish to leave.
to convey (a message) in a sign language.
Obsolete. to direct or appoint by a sign.
verb (used without object)
to write one's signature, as a token of agreement, obligation, receipt, etc.:
to sign for a package.
to make a sign or signal:
He signed to her to go away.
to employ a sign language for communication.
to obligate oneself by signature:
He signed with another team for the next season.
Verb phrases
sign away/over, to assign or dispose of by affixing one's signature to a document:
She signed over her fortune to the church.
sign in, to record or authorize one's arrival (or departure) by signing a register.
Also, sign out.
sign off,
  1. to withdraw, as from some responsibility or connection.
  2. to cease radio or television broadcasting, especially at the end of the day.
  3. Informal. to become silent:
    He had exhausted conversation topics and signed off.
  4. to indicate one's approval explicitly if not formally:
    The president is expected to sign off on the new agreement.
sign on,
  1. to employ; hire.
  2. to bind oneself to work, as by signing a contract:
    He signed on as a pitcher with a major-league team.
  3. to start radio or television broadcasting, especially at the beginning of the day.
  4. Computers. log1 (def 17a).
sign up, to enlist, as in an organization or group; to register or subscribe:
to sign up for the navy; to sign up for class.
1175-1225; (noun) Middle English signe < Old French < Latin signum mark, sign, ensign, signal, image; (v.) Middle English signen to mark with a sign, especially the sign of the cross < Old French signer < Latin signāre to mark with a sign, inscribe, affix a seal to, derivative of signum
Related forms
signless, adjective
signlike, adjective
postsign, verb (used with object)
unsigned, adjective
Can be confused
sign, sing (see synonym study at the current entry)
1. trace, hint, suggestion. 1, 4. signal. 10. indication, hint, augury. Sign, omen, portent name that which gives evidence of a future event. Sign is a general word for whatever gives evidence of an event—past, present, or future: Dark clouds are a sign of rain or snow. An omen is an augury or warning of things to come; it is used only of the future, in general, as good or bad: birds of evil omen. Portent, limited, like omen, to prophecy of the future, may be used of a specific event, usually a misfortune: portents of war. Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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British Dictionary definitions for sign in

sign in

verb (adverb)
to sign or cause to sign a register, as at a hotel, club, etc
to make or become a member, as of a club


something that indicates or acts as a token of a fact, condition, etc, that is not immediately or outwardly observable
an action or gesture intended to convey information, a command, etc
  1. a board, placard, etc, displayed in public and inscribed with words or designs intended to inform, warn, etc
  2. (as modifier): a sign painter
an arbitrary or conventional mark or device that stands for a word, phrase, etc
(maths, logic)
  1. any symbol indicating an operation: a plus sign, an implication sign
  2. the positivity or negativity of a number, quantity, or expression: subtraction from zero changes the sign of an expression
an indication or vestige: the house showed no signs of being occupied
a portentous or significant event
an indication, such as a scent or spoor, of the presence of an animal
(med) any objective evidence of the presence of a disease or disorder Compare symptom (sense 1)
(astrology) Compare sign of the zodiac
to write (one's name) as a signature to (a document, etc) in attestation, confirmation, ratification, etc
(intransitive) often foll by to. to make a sign; signal
to engage or be engaged by written agreement, as a player for a team, etc
(transitive) to outline in gestures a sign over, esp the sign of the cross
(transitive) to indicate by or as if by a sign; betoken
(intransitive) to use sign language
Derived Forms
signable, adjective
Word Origin
C13: from Old French signe, from Latin signum a sign
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for sign in



early 13c., "gesture or motion of the hand," especially one meant to communicate something, from Old French signe "sign, mark," from Latin signum "identifying mark, token, indication, symbol; proof; military standard, ensign; a signal, an omen; sign in the heavens, constellation," according to Watkins, literally "standard that one follows," from PIE *sekw-no-, from root *sekw- (1) "to follow" (see sequel).

Ousted native token. Meaning "a mark or device having some special importance" is recorded from late 13c.; that of "a miracle" is from c.1300. Zodiacal sense in English is from mid-14c. Sense of "characteristic device attached to the front of an inn, shop, etc., to distinguish it from others" is first recorded mid-15c. Meaning "token or signal of some condition" (late 13c.) is behind sign of the times (1520s). In some uses, the word probably is a shortening of ensign. Sign language is recorded from 1847; earlier hand-language (1670s).



c.1300, "to make the sign of the cross," from Old French signier "to make a sign (to someone); to mark," from Latin signare "to set a mark upon, mark out, designate; mark with a stamp; distinguish, adorn;" figuratively "to point out, signify, indicate," from signum (see sign (n.)). Sense of "to mark, stamp" is attested from mid-14c.; that of "to affix one's name" is from late 15c. Meaning "to communicate by hand signs" is recorded from 1700. Related: Signed; signing.



1968, from the verbal phrase; see sign (v.) + in (adv.).

Online Etymology Dictionary, © 2010 Douglas Harper
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sign in in Medicine

sign (sīn)

  1. See symptom.

  2. Something that suggests the presence or existence of a fact, condition, or quality.

  3. A trace or vestige, as of disease or life.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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sign in in Science
  1. A body manifestation, usually detected on physical examination or through laboratory tests or xrays, that indicates the presence of abnormality or disease. Compare symptom.

  2. See symbol. See Table at symbol.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Slang definitions & phrases for sign in


Related Terms

the high sign

The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D.
Copyright (C) 2007 by HarperCollins Publishers.
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Idioms and Phrases with sign in

sign in

Record one's arrival by signing a register, as in He signed in both himself and his wife. [ c. 1930 ]
For the antonym, see sign out
The American Heritage® Idioms Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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