ABSTAINER, n. A weak person who yields to the temptation of denying
himself a pleasure. A total abstainer is one who abstains from
everything but abstention, and especially from inactivity in the
affairs of others.
ACCORD, n. Harmony.
ACCORDION, n. An instrument in harmony with the sentiments of an
assassin.
ACHIEVEMENT, n. The death of endeavor and the birth of disgust.
ADMIRATION, n. Our polite recognition of another's resemblance to
ourselves.
ALONE, adj. In bad company.
APOLOGIZE, v.i. To lay the foundation for a future offence.
GRAVITATION, n. The tendency of all bodies to approach one another
with a strength proportion to the quantity of matter they contain --
the quantity of matter they contain being ascertained by the strength
of their tendency to approach one another. This is a lovely and
edifying illustration of how science, having made A the proof of B,
makes B the proof of A.
HOMICIDE, n. The slaying of one human being by another. There are
four kinds of homocide: felonious, excusable, justifiable, and
praiseworthy, but it makes no great difference to the person slain
whether he fell by one kind or another -- the classification is for
advantage of the lawyers.
WAR, n. A by-product of the arts of peace.
All quoted from Ambrose Bierce
For the full dictionary, goto The Devil's DictionaryI should note that after the A's I just skimmed very quickly, there are many more gems among the other letters.