Today's Word of the Day means...


a prefix occurring in loanwords from Latin, where it meant “toward” and indicated direction, tendency, or addition: adjoin . Usually assimilated to the following consonant; see a-5 , ac-, af-, ag-, al-, an-2 , ap-1 , ar-, as-, at-.
< Latin ad, ad- (preposition and prefix) to, toward, at, about; cognate with at1 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
Cite This Source
British Dictionary definitions for ad-


to; towards adsorb, adverb
near; next to adrenal
Word Origin
from Latin: to, towards. As a prefix in words of Latin origin, ad- became ac-, af-, ag-, al-, an-, acq-, ar-, as-, and at- before c, f, g, l, n, q, r, s, and t, and became a- before gn, sc, sp, st
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
Cite This Source
Word Origin and History for ad-
prefix expressing direction toward or in addition to, from L. ad "to, toward," from PIE *ad- "to, near, at" (cognate with O.E. æt; see at). Simplified to a- before sc-, sp- and st-; modified to ac- before many consonants and then re-spelled af-, ag-, al- etc., in conformity with the following consonant (e.g. affection, aggression). In O.Fr., reduced to a- in all cases, but written forms were refashioned after L. in 14c. in Fr., and 15c. in Eng. words picked up from O.Fr. In many cases pronunciation followed the shift.
Online Etymology Dictionary, © 2010 Douglas Harper
Cite This Source
ad- in Medicine

ad- pref.

  1. or ac- or af- or ag- or al- or ap- or as- or at- Toward; to. Before c, f, g, k, l, p, q, s, and t, ad- is usually assimilated to ac-, af-, ag-, ac-, al-, ap-, ac-, as-, and at-, respectively: adductor, acclimation, agglutinant.

  2. Near; at: adrenal.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Cite This Source

Word of The Day

Difficulty index for ad-

Few English speakers likely know this word

Word Value for ad

Scrabble Words With Friends

Quotes with ad-