Abraham-man was an old term for mendicant lunatics, or, more commonly, frauds who wandered England shamming madness so as to collect alms (1560s). According to the old explanation of the name (from at least 1640s), they originally were from Bethlehem Hospital, where in early times there was an Abraham ward or room for such persons, but the ward might have been named for the beggars.
late 14c., orange bright star in the constellation Bootes (also used of the whole constellation), from Latin Arcturus, from Greek Arktouros, literally "guardian of the bear" (the bright star was anciently associated with nearby Ursa Major, the "Big Dipper," which it seems to follow across the sky). For first element see arctic; second element is Greek ouros "watcher, guardian, ward," from PIE root *wer- (3) "perceive, watch out for." It is fourth-brightest of the fixed stars. The double nature of the great bear/wagon (see Big Dipper) has given two different names to the constellation that follows it: Arktouros "bear-ward" and Bootes "the wagoner" (from Greek, ultimately from PIE root *gwou- "ox, bull, cow").
Arcturus in the Bible (Job ix.9 and xxxviii.32) is a mistranslation by Jerome (continued in KJV) of Hebrew 'Ayish, which refers to what we see as the "bowl" of the Big Dipper. In Israel and Arabia, the seven stars of the Great Bear seem to have been a bier (the "bowl") followed by three mourners. In the Septuagint it was translated as Pleiada, which is equally incorrect.
masc. proper name, from Latin, from Greek Alexandros "defending men," from alexein "to ward off, keep off, turn (something) away, defend, protect" + anēr (genitive andros) "man" (from PIE root *ner- (2) "man"). The first element perhaps is related to Greek alke "protection, help, strength, power, courage," alkimos "strong;" and cognate with Sanskrit raksati "protects," Old English ealgian "to defend."
As a kind of cocktail recipe featuring crème de cacao and cream, Alexander is attested from 1913; the reason for the name is unclear.