From c. 1300 as "physical shape (of something), contour, outline," of a person, "shape of the body;" also "appearance, likeness;" also "the imprint of an object." From c. 1300 as "correct or appropriate way of doing something; established procedure; traditional usage; formal etiquette." Mid-14c. as "instrument for shaping; a mould;" late 14c. as "way in which something is done," also "pattern of a manufactured object." Used widely from late 14c. in theology and Platonic philosophy with senses "archetype of a thing or class; Platonic essence of a thing; the formative principle." From c. 1300 in law, "a legal agreement; terms of agreement," later "a legal document" (mid-14c.). Meaning "a document with blanks to be filled in" is from 1855. From 1590s as "systematic or orderly arrangement;" from 1610s as "mere ceremony." From 1550s as "a class or rank at school" (from sense "a fixed course of study," late 14c.). Form-fitting (adj.) in reference to clothing is from 1893.
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"]
"form again, remake, reconstruct, re-create or re-establish," mid-14c., from re- "back, again" + form (v.). Intransitive sense of "form again, get into order or line again" also is from mid-14c. Spelled with a hyphen from 17c. to distinguish it from the specific sense in reform; this is the original meaning of that word, still in use but now with full pronunciation of the prefix. Related: Re-formed; re-forming; re-formation.