"containing no water," 1809, a modern coinage from Greek an- "not, without" (see an- (1)) + hydor "water" (from PIE root *wed- (1) "water; wet") + -ous. Greek did have anhydros "waterless," used of arid lands or corpses that had not been given proper funeral rites.

"resembling or pertaining to birds," 1861, from Latin avis "bird" (from PIE root *awi- "bird") + -an.

1836, from Cetacea, name of the order of marine mammals, + -an. As an adjective, "pertaining to the whale," from 1839.

also amoebean, "alternating, answering alternately," 1650s, from Greek amoibē "change, alteration; exchange" (see amoeba) + -an.

"deficiency of blood in a living body," alternative (chiefly U.S.) spelling of anaemia (q.v.); also see æ (1). As a genus of plants, Modern Latin, from Greek aneimon "unclad," from an- "without" (see an- (1)) + eima "a dress, garment" (see wear (v.)).

c. 1600, "without a name;" 1670s, "published under no name, of unknown authorship," from Late Latin anonymus, from Greek anonymos "without a name," from an- "without" (see an- (1)) + onyma, Æolic dialectal form of onoma "name" (from PIE root *no-men- "name").

1560s, "characterized by intemperate drinking;" see Bacchanalia + -an. From 1620s as "pertaining to Bacchanals." As a noun from 1610s, "participant in the Bacchanalia."

1590s, from Hercules + -an. "Of enormous size or strength or great courage," also sometimes "very difficult or dangerous," in allusion to the hero's labors.

"pertaining to or resembling the unceasingly recurring and fruitless labors of Sisyphus," 1630s, from Sisyphus + -an. The earlier form was Sisyphian (1590s).

"deviating from a general rule," 1640s, from Late Latin anomalus, from Greek anomalos "uneven, irregular," from an- "not" (see an- (1)) + homalos "even," from homos "same" (from PIE root *sem- (1) "one; as one, together with"). Related: Anomalously; anomalousness.