This letter, in English, is used for several different vowel sounds. See Guide to pronunciation, §§ 43-74. The regular long a, as in fate, etc., is a comparatively modern sound, and has taken the place of what, till about the early part of the 17th century, was a sound of the quality of ä (as in far). [ 1913 Webster ]

2. (Mus.) The name of the sixth tone in the model major scale (that in C), or the first tone of the minor scale, which is named after it the scale in A minor. The second string of the violin is tuned to the A in the treble staff. -- A sharp (A♯) is the name of a musical tone intermediate between A and B. -- A flat (A♭) is the name of a tone intermediate between A and G. [ 1913 Webster ]

A per se (L. per se by itself), one preëminent; a nonesuch. [ Obs. ] [ 1913 Webster ]

O fair Creseide, the flower and A per se
Of Troy and Greece. Chaucer. [ 1913 Webster ]

2. [ Originally the preposition a (an, on). ] In each; to or for each; as, “twenty leagues a day”, “a hundred pounds a year”, “a dollar a yard”, etc. [ 1913 Webster ]

2. In process of; in the act of; into; to; -- used with verbal substantives in -ing which begin with a consonant. This is a shortened form of the preposition an (which was used before the vowel sound); as in a hunting, a building, a begging. “Jacob, when he was a dying” Heb. xi. 21. “We'll a birding together.” “ It was a doing.” Shak. “He burst out a laughing.” Macaulay. The hyphen may be used to connect a with the verbal substantive (as, a-hunting, a-building) or the words may be written separately. This form of expression is now for the most part obsolete, the a being omitted and the verbal substantive treated as a participle. [ 1913 Webster ]

A merry heart goes all the day,
Your sad tires in a mile-a. Shak. [ 1913 Webster ]

Besides these, there are other sources from which the prefix a takes its origin. [ 1913 Webster ]

A 1 is also applied colloquially to other things to imply superiority; prime; first-class; first-rate. [ 1913 Webster ]

2. Alcoholics Anonymous. [ Acronym. ] [ WordNet 1.5 ]

2. (Bot.) A plant with a tall flowering stem; esp. the great mullein, or hag-taper, and the golden-rod. [ 1913 Webster ]

2. Behind; in the rear. Knolles. [ 1913 Webster ]

3. (Naut.) Backward against the mast; -- said of the sails when pressed by the wind. Totten. [ 1913 Webster ]

To be taken aback. (a) To be driven backward against the mast; -- said of the sails, also of the ship when the sails are thus driven. (b) To be suddenly checked, baffled, or discomfited. Dickens. [ 1913 Webster ]

2. A calculating table or frame; an instrument for performing arithmetical calculations by balls sliding on wires, or counters in grooves, the lowest line representing units, the second line, tens, etc. It is still employed in China. [ 1913 Webster ]

3. (Arch.) (a) The uppermost member or division of the capital of a column, immediately under the architrave. See Column. (b) A tablet, panel, or compartment in ornamented or mosaic work. [ 1913 Webster ]

4. A board, tray, or table, divided into perforated compartments, for holding cups, bottles, or the like; a kind of cupboard, buffet, or sideboard. [ 1913 Webster ]

Abacus harmonicus (Mus.), an ancient diagram showing the structure and disposition of the keys of an instrument. Crabb. [ 1913 Webster ]

2. Hell; the bottomless pit. [ Poetic ] [ 1913 Webster ]

In all her gates, Abaddon rues
Thy bold attempt. Milton. [ 1913 Webster ]

Abaft the beam. See under Beam. [ 1913 Webster ]

2. To estrange; to withdraw. [ Obs. ] [ 1913 Webster ]

3. To cause alienation of (mind). Sandys. [ 1913 Webster ]

Enforced the kingdom to aband. Spenser. [ 1913 Webster ]

2. To banish; to expel. [ Obs. ] Mir. for Mag. [ 1913 Webster ]

That he might . . . abandon them from him. Udall. [ 1913 Webster ]

Being all this time abandoned from your bed. Shak. [ 1913 Webster ]

2. To give up absolutely; to forsake entirely ; to renounce utterly; to relinquish all connection with or concern on; to desert, as a person to whom one owes allegiance or fidelity; to quit; to surrender. [ 1913 Webster ]

Hope was overthrown, yet could not be abandoned. I. Taylor. [ 1913 Webster ]

3. Reflexively: To give (one's self) up without attempt at self-control; to yield (one's self) unrestrainedly; -- often in a bad sense. [ 1913 Webster ]

He abandoned himself . . . to his favorite vice. Macaulay. [ 1913 Webster ]

4. (Mar. Law) To relinquish all claim to; -- used when an insured person gives up to underwriters all claim to the property covered by a policy, which may remain after loss or damage by a peril insured against. [ 1913 Webster ]

Syn. -- To give up; yield; forego; cede; surrender; resign; abdicate; quit; relinquish; renounce; desert; forsake; leave; retire; withdraw from. -- To Abandon, Desert, Forsake. These words agree in representing a person as giving up or leaving some object, but differ as to the mode of doing it. The distinctive sense of abandon is that of giving up a thing absolutely and finally; as, to abandon one's friends, places, opinions, good or evil habits, a hopeless enterprise, a shipwrecked vessel. Abandon is more widely applicable than forsake or desert. The Latin original of desert appears to have been originally applied to the case of deserters from military service. Hence, the verb, when used of persons in the active voice, has usually or always a bad sense, implying some breach of fidelity, honor, etc., the leaving of something which the person should rightfully stand by and support; as, to desert one's colors, to desert one's post, to desert one's principles or duty. When used in the passive, the sense is not necessarily bad; as, the fields were deserted, a deserted village, deserted halls. Forsake implies the breaking off of previous habit, association, personal connection, or that the thing left had been familiar or frequented; as, to forsake old friends, to forsake the paths of rectitude, the blood forsook his cheeks. It may be used either in a good or in a bad sense. [ 1913 Webster ]

2. Self-abandoned, or given up to vice; extremely wicked, or sinning without restraint; irreclaimably wicked ; as, an abandoned villain. [ 1913 Webster ]

Syn. -- Profligate; dissolute; corrupt; vicious; depraved; reprobate; wicked; unprincipled; graceless; vile. -- Abandoned, Profligate, Reprobate. These adjectives agree in expressing the idea of great personal depravity. Profligate has reference to open and shameless immoralities, either in private life or political conduct; as, a profligate court, a profligate ministry. Abandoned is stronger, and has reference to the searing of conscience and hardening of heart produced by a man's giving himself wholly up to iniquity; as, a man of abandoned character. Reprobate describes the condition of one who has become insensible to reproof, and who is morally abandoned and lost beyond hope of recovery. [ 1913 Webster ]

God gave them over to a reprobate mind. Rom. i. 28. [ 1913 Webster ]