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.
"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.