expansion (n.)

1610s, "anything spread out;" 1640s, "act of expanding," from French expansion, from Late Latin expansionem (nominative expansio) "a spreading out," noun of action from past participle stem of Latin expandere "to spread out, unfold, expand," from ex "out" (see ex-) + pandere "to spread, stretch" (from nasalized form of PIE root *pete- "to spread").