1620s, "given to profuse expenditure," from expense (n.) + -ive. Meaning "costly, requiring profuse expenditure" is from 1630s. Earlier was expenseful (c. 1600). Expenseless was in use mid-17c.-18c., but there seems now nothing notable to which it applies, and the dictionaries label it "obsolete." Related: Expensively; expensiveness.