Can be confused:expand, expend (see synonym note at the current entry).
Synonyms 1. extend, swell, enlarge. See increase.Expand,dilate,distend,inflate imply becoming larger and filling more space. To expand is to spread out, usually in every direction: to expand one's chest. To dilate is especially to increase the width or circumference, and applies to space enclosed within confines or to hollow bodies: to dilate the pupils of the eyes. To distend is to stretch, often beyond the point of natural expansion: to distend an artery. To inflate is to blow out or swell a hollow body with air or gas: to inflate a balloon.
early 15c., "spread out, spread flat," from Anglo-Fr. espaundre, from L. expandere "to spread out," from ex- "out" + pandere "to spread." Sense of "grow larger" first recorded 1640s. Related: Expanded; expanding.