smell a rat. rat(def 6).

Origin of smell

1125–75; early Middle English smell, smull (noun), smellen, smullen (v.) < ?
Related formssmell·a·ble, adjectivesmell-less, adjectiveout·smell, verb (used with object), out·smelled or out·smelt, out·smel·ling.un·smelled, adjectiveun·smell·ing, adjective

Synonyms for smell

13. See odor. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Related Words for smell up

offend, reek, funk

British Dictionary definitions for smell up


verb smells, smelling, smelt or smelled

(tr) to perceive the scent or odour of (a substance) by means of the olfactory nerves
(copula) to have a specified smell; appear to the sense of smell to bethe beaches smell of seaweed; some tobacco smells very sweet
(intr often foll by of) to emit an odour (of)the park smells of flowers
(intr) to emit an unpleasant odour; stink
(tr often foll by out) to detect through shrewdness or instinct
(intr) to have or use the sense of smell; sniff
(intr foll by of) to give indications (of)he smells of money
(intr; foll by around, about, etc) to search, investigate, or pry
(copula) to be or seem to be untrustworthy or corrupt
smell a rat to detect something suspicious


that sense (olfaction) by which scents or odours are perceivedRelated adjective: olfactory
anything detected by the sense of smell; odour; scent
a trace or indication
the act or an instance of smelling
Derived Formssmeller, noun

Word Origin for smell

C12: of uncertain origin; compare Middle Dutch smölen to scorch
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

Word Origin and History for smell up



late 12c., "emit or perceive an odor," not found in Old English, perhaps cognate with Middle Dutch smolen, Low German smelen "to smolder" (see smolder). However, OED says "no doubt of Old English origin, but not recorded, and not represented in any of the cognate languages." Related: Smelled or smelt; smelling.

Smelling salts (1840), used to revive the woozy, typically were a scented preparation of carbonate of ammonia. Smell-feast (n.) "one who finds and frequents good tables, one who scents out where free food is to be had" is from 1510s ("very common" c.1540-1700, OED). Smell-smock "licentious man" was in use c.1550-c.1900. To smell a rat "be suspicious" is from 1540s.



"odor, aroma, stench," late 12c.; "faculty of perceiving by the nose," c.1200; see smell (v.). Ousted Old English stenc (see stench) in most senses.

Online Etymology Dictionary, © 2010 Douglas Harper

smell up in Medicine




To perceive the scent of something by means of the olfactory nerves.


The sense by which odors are perceived; the olfactory sense.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Idioms and Phrases with smell up

smell up

Also, stink up. Cause a bad odor, as in These onions smell up the whole house, or Your old sneakers are stinking up the closet; throw them out. [Mid-1900s]


In addition to the idioms beginning with smell

  • smell a rat
  • smell fishy
  • smell to high heaven
  • smell up

also see:

  • come up (smelling like) roses
  • stink (smell) to high heaven
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.