prophylacticyoudaoicibaDictYouDict[prophylactic 词源字典]
prophylactic: [16] Prophylactic comes from Greek prophulaktikós, a derivative of the verb prophulássein. This meant literally ‘keep guard in front of a place’, and hence ‘take precautions against’. It was formed from the prefix pro- ‘before’ and phulássein ‘guard’.
[prophylactic etymology, prophylactic origin, 英语词源]
anaphylactic (adj.)youdaoicibaDictYouDict
1905, with -ic + medical Latin noun anaphylaxis "exaggerated susceptibility," from French anaphylaxie (1902), from Greek ana- (see ana-) + phylaxis "watching, guarding" (compare prophylactic). Anaphylactic shock is attested by 1916.
anaphylaxis (n.)youdaoicibaDictYouDict
see anaphylactic.
phylactery (n.)youdaoicibaDictYouDict
late 14c., "small leathern box containing four Old Testament texts," from Old French filatiere (12c.) and directly from Medieval Latin philaterium, from Late Latin phylacterium "reliquary," from Greek phylacterion "safeguard, amulet," noun use of neuter of adjective phylakterios "serving as a protection," from phylakter "watcher, guard," from phylassein "to guard or ward off," from phylax (genitive phylakos) "guard," of unknown origin. Sometimes worn on the forehead, based on a literal reading of scripture:
Ye shall bind them [my words] for a sign upon your hands, and they shall be for frontlets between your eyes. [Deut. xi:18]
prophylactic (adj.)youdaoicibaDictYouDict
1570s, originally of medicines, "that tends to prevent disease," from Middle French prophylactique (16c.) and directly as a Latinized borrowing of Greek prophylaktikos "precautionary," from prophylassein "keep guard before, ward off, be on one's guard," from pro- "before" (see pro-) + phylassein, Ionic variant of phylattein "to watch over, to guard," but also "cherish, keep, remain in, preserve" (see phylactery).

The noun is first recorded 1640s, "a medicine or treatment to prevent disease;" meaning "condom" is from 1943, replacing earlier preventive (1822), preventative (1901). Condoms originally were used more to thwart contagious disease than to prevent pregnancy.
prophylaxis (n.)youdaoicibaDictYouDict
"preventive treatment of disease," 1746, Modern Latin, from Greek pro (see pro-) + phylaxis "a watching, guarding" (see prophylactic).
phylarchyoudaoicibaDictYouDict
"Chiefly Ancient Greek History . In ancient Greece: the ruler or leader of a phyle. Also more generally: a tribal or clan chief", Mid 16th cent.; earliest use found in Ralph Robinson (1520–1577), translator. From classical Latin phȳlarchus leader or chief of a tribe, chief official of a Greek phyle from ancient Greek ϕύλαρχος chief official of a phyle, (in Attica) commander of the cavalry of a phyle from ϕυλή tribe + -αρχος.
phacoanaphylaxisyoudaoicibaDictYouDict
"Hypersensitivity to proteins released from the lens of the eye; inflammation of the eye (endophthalmitis or uveitis) caused by this", 1940s; earliest use found in American Journal of Ophthalmology. From phaco- + anaphylaxis, after phacoanaphylactic.
phacoanaphylacticyoudaoicibaDictYouDict
"Caused by, involving, or relating to hypersensitivity to lens proteins", 1920s. From phaco- + anaphylactic, after scientific Latin phacoanaphylacticus.