"secret word appointed as a sign to distinguish friend from foe," 1798, from pass (v.) + word (n.).
Entries linking to password
pass v.
late 13c., passen (transitive), "to go by (something)," also "to cross over," from Old French passer "to pass" (11c.), from Vulgar Latin *passare "to step, walk, pass" (source also of Spanish pasar, Italian passare), from Latin passus "step, pace" (from PIE root *pete- "to spread").
Intransitive sense of "to go on, to move forward, make one's way" is attested from c. 1300. The figurative sense of "to experience, undergo" (as in pass the time) is recorded from late 14c. Sense of "to go through an examination successfully" is from early 15c. Meaning "decline to do something" is attested from 1869, originally in cards (euchre). In football, hockey, soccer, etc., the meaning "to transfer the ball or puck to another player" is from c. 1865. Related: Passed; passing.
The meaning "to be thought to be something one is not" (especially in a racial sense) is from 1935, from pass oneself off(as), which is attested by 1809. The general verb sense of "to be accepted as equivalent" is from 1590s. Pass up "decline, refuse" is attested from 1896. Pass the buck is from 1865, said to be poker slang reference to the buck horn-handled knife that was passed around to signify whose turn it was to deal. Pass the hat "seek contributions" is from 1762. Pass-fail as a grading method is attested from 1955, American English.
word n.
Old English word "speech, talk, utterance, sentence, statement, news, report, word," from Proto-Germanic *wurda- (source also of Old Saxon, Old Frisian word, Dutch woord, Old High German, German wort, Old Norse orð, Gothic waurd), from PIE *were- (3) "speak, say" (see verb).
The meaning "promise" was in Old English, as was the theological sense. In the plural, the meaning "verbal altercation" (as in have words with someone) dates from mid-15c. Word-processor first recorded 1971; word-processing is from 1972; word-wrap is from 1977. A word to the wise is from Latin phrase verbum sapienti satis est "a word to the wise is enough." Word-for-word "in the exact word or terms" is late 14c. Word of mouth "spoken words, oral communication" (as distinguished from written words) is by 1550s.
It is dangerous to leave written that which is badly written. A chance word, upon paper, may destroy the world. Watch carefully and erase, while the power is still yours, I say to myself, for all that is put down, once it escapes, may rot its way into a thousand minds, the corn become a black smut, and all libraries, of necessity, be burned to the ground as a consequence. [William Carlos Williams, "Paterson"]