a reduced form of the Old English preposition on, meaning “on,” “in,” “into,” “to,” “toward,” preserved before a noun in a prepositional phrase, forming a predicate adjective or an adverbial element (afoot; abed; ashore; aside; away), or before an adjective (afar; aloud; alow), as a moribund prefix with a verb (acknowledge), and in archaic and dialectal use before a present participle in -ing (set the bells aringing); and added to a verb stem with the force of a present participle (ablaze; agape; aglow; astride; and originally, awry).
Definition for a- (2 of 7)
a reduced form of the Old English preposition of: akin; afresh; anew.
Origin of a-2
Middle English; see a3
Definition for a- (3 of 7)
an old point-action prefix, not referring to an act as a whole, but only to the beginning or end: She arose (rose up). They abided by their beliefs (remained faithful to the end).
Definition for a- (4 of 7)
variant of ab- before p and v: aperient; avert.
Definition for a- (5 of 7)
variant of ad-, used: (1) before sc, sp, st (ascend) and (2) in words of French derivation (often with the sense of increase, addition): amass.
Definition for a- (6 of 7)
variant of an-1 before a consonant, meaning “not,” “without”: amoral; atonal; achromatic.
Definition for a- (7 of 7)
atomic (used in combination): A-bomb; A-plant.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020
British Dictionary definitions for a- (1 of 2)
before a vowel an-
not; without; opposite toatonal; asocial
Word Origin for a-
from Greek a-, an- not, without
British Dictionary definitions for a- (2 of 2)
on; in; towardsafoot; abed; aground; aback
literary, or archaic (used before a present participle) in the act or process ofcome a-running; go a-hunting
in the condition or state ofafloat; alive; asleep
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
Medical definitions for a-
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
Scientific definitions for a-
A prefix meaning without or not when forming an adjective (such as amorphous, without form, or atypical, not typical), and absence of when forming a noun (such as arrhythmia, absence of rhythm). Before a vowel or h it becomes an- (as in anhydrous, anoxia).
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.