[ gran-fah-ther, grand- ]
See synonyms for grandfather on
  1. the father of one's father or mother.

  2. a forefather.

  1. the founder or originator of a family, species, type, etc.; the first of one's or its kind, or the one being longest in existence: the grandfather of all steam locomotives.

verb (used with object)
  1. to exempt (something or someone) from new legislation, restrictions, or requirements: The law grandfathered all banks already operating at the time of passage. He was grandfathered into the pension plan.

Origin of grandfather

late Middle English word dating back to 1375–1425; see origin at grand-, father Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use grandfather in a sentence

British Dictionary definitions for grandfather


/ (ˈɡrænˌfɑːðə, ˈɡrænd-) /

  1. the father of one's father or mother

  2. (often plural) a male ancestor

  1. (often capital) a familiar term of address for an old man

  2. dialect a caterpillar or woodlouse

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