[Middle English, from Latin adiacēns, adiacent-, present participle of adiacēre, to lie near : ad-, ad- + iacēre, to lie; see yē- in Indo-European roots.] ad·ja'cent·ly adv.
c.1430, from L. adjacentem (nom. adjacens) "lying at," prp. of adjacere "lie near," from ad- "to" + jacere "to lie, rest," lit. "to throw" (see jet (v.)), with notion of "to cast (oneself) down."