"one who accuses or blames," especially "person who formally accuses another of an offense before a magistrate," mid-14c., accusour, from Anglo-French accusour, Old French accusor, from Latin accusator, agent-noun from past-participle stem of accusare (see accuse).
"to score" in sports, 1922, originally in tennis, from ace (n.). This probably is the source of the student slang verb sense of "get high marks" (1959). Related: Aced; acing.
c. 1300, "one at dice," from Old French as "one at dice" (12c.), from Latin as "a unit, one, a whole, unity;" also the name of a small Roman coin (originally a rectangular bronze plaque weighing one pound, it eventually was reduced by depreciation to half an ounce; in imperial times it became a round coin). The Latin word also is the source of Spanish as, Italian asso, German ass, Dutch aas, Danish es. It is perhaps originally Etruscan and related to Greek heis "one" (from PIE root *sem- (1) "one, as one"), or it might have been taken directly into Latin from the Greek word.
In English, it meant the side of the die with only one mark before it meant the playing card with one pip (1530s). Because this was the lowest roll at dice, ace was used metaphorically in Middle English for "bad luck" or "something of no value;" but as the ace often is the highest playing card, the extended senses based on "excellence, good quality" arose 18c. as card-playing became popular. Ace in the hole in the figurative sense of "concealed advantage" is attested from 1904, from crooked stud-poker deals.
The meaning "outstanding pilot" dates from 1917 (technically, in World War I aviators' jargon, one who has brought down 10 enemy planes, though originally in reference to 5 shot down), from French l'ace (1915), which, according to Bruce Robertson (ed.) "Air Aces of the 1914-1918 War" was used in prewar French sporting publications for "top of the deck" boxers, cyclists, etc. The sports meaning "point scored" (1819) led to sense of "unreturnable serve" (by 1889).
The names are thus formally adjectives, Latin animalia "animals" (a neuter plural noun) being understood. Thus Crustacea "shellfish" are *crustacea animalia "crusty animals."
In botany, the suffix is -aceae, from the fem. plural of -aceus, forming orders or families of plants (Rosaceae, etc.) with a presumed plantae "plants," which is a fem. plural.
late 14c., name of the potter's field near Jerusalem that was purchased with the money Judas Iscariot took to betray Jesus, literally "place of bloodshed," from Greek Akeldama, rendering an Aramaic (Semitic) name akin to Syriac haqal dema "the field of blood." So called for being purchased with the blood-money.