"to rise from or out of anything that surrounds, covers, or conceals; come forth; appear, as from concealment," 1560s, from French émerger and directly from Latin emergere "bring forth, bring to light," intransitively "arise out or up, come forth, come up, come out, rise," from assimilated form of ex "out" (see ex-) + mergere "to dip, sink" (see merge). The notion is of rising from a liquid by virtue of buoyancy. Related: Emerged; emerging.
"reappearance, act of emerging," 1630s, noun of action from past-participle stem of Latin emergere "to rise out or up" (see emerge). Originally of eclipses and occultations.
in botany, "standing out of or raised above water, raised partially above surrounding leaves," 1680s, formed as if a past-participle adjective, from Latin emersus, past participle of emergere "rise out or up" (see emerge).
"to have actual being of any kind, actually be at a certain moment or throughout a certain period of time," c. 1600, from French exister (17c.), from Latin existere/exsistere "to step out, stand forth, emerge, appear; exist, be" (see existence). "The late appearance of the word is remarkable" [OED]. Middle English often used ibēn, ibeon (based on be) for "to exist." Related: Existed; existing.