enlarge v.

word-forming element meaning "in; into," from French and Old French en-, from Latin in- "in, into" (from PIE root *en "in"). Typically assimilated before -p-, -b-, -m-, -l-, and -r-. Latin in- became en- in French, Spanish, Portuguese, but remained in- in Italian.

Also used with native and imported elements to form verbs from nouns and adjectives, with a sense "put in or on" (encircle), also "cause to be, make into" (endear), and used as an intensive (enclose). Spelling variants in French that were brought over into Middle English account for parallels such as ensure/insure, and most en- words in English had at one time or another a variant in in-, and vice versa.

c. 1200, of areas, "great in expanse," of persons, "bountiful, inclined to give or spend freely," from Old French large "broad, wide; generous, bounteous" (12c.), from Latin largus "abundant, copious, plentiful; bountiful, liberal in giving, generous" (source also of Spanish largo "long," Italian largo "wide"), a word of unknown origin.

The modern English meanings "extensive; big in overall size; great in number" emerged 14c. Adjective phrase larger-than-life first attested 1840 (bigger than life is from 1640s). Large-handed has meant both "grasping, greedy" (c. 1600) and "generous, liberal" (1620s); also "having large hands" (1896). Living large is a modern colloquial expression (1994 in African-American vernacular), but large in the sense of "prodigal, lavish" is from late 14c. and, of circumstances, "comfortable, easy" from 1738, and in more recent use Farmer and Henley ("Slang and Its Analogues") have it as "impressively, to excess" from 1852.

In mod.Eng., a general designation for considerable magnitude, used instead of great when it is not intended to convey the emotional implication now belonging to that word. [OED]

An older sense of "freedom from prison or restraining influence" is preserved in at large "at (one's) liberty, free from imprisonment or confinement free to move openly" (late 14c.). The phrase, with the meaning "free or at liberty in a general way (without particulars)" is from 1620s; specifically of electors from 1741, American English.

1530s, "a release from confinement," from enlarge in the secondary Middle English sense "release a prisoner" (mid-15c.) + -ment. Meaning "act of increasing in size" is from 1560s. Photographic sense "picture of a larger size than the negative from which it was made" is from 1866.