[ sahyn-in ]

  1. 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 Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use sign-in in a sentence

British Dictionary definitions for sign in

sign in

  1. to sign or cause to sign a register, as at a hotel, club, etc

  2. to make or become a member, as of a club

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

Other Idioms and Phrases with 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 Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.