"occupying the same space or duration of time," 1771, from co- + extensive.
Entries linking to coextensive
co-
in Latin, the form of com- "together, with" in compounds with stems beginning in vowels, h-, and gn-; see com-. Taken in English from 17c. as a living prefix meaning "together, mutually, in common," and used promiscuously with native words (co-worker) and Latin-derived words not beginning with vowels (codependent), including some already having it (co-conspirator).
extensive adj.
"vast, far-reaching;" c. 1600 of immaterial, c. 1700 of material things; from Late Latin extensivus, from extens-, past-participle stem of Latin extendere "to stretch out, spread" (see extend). Earlier in a medical sense, "characterized by swelling" (early 15c.). Related: Extensively; extensiveness.