1510s, "to compact into one body," from L. consolidat-, pp. stem of consolidare, from con- "together" + solidare "to make solid" (see consolidation). Meaning "to make firm or strong" is from c.1540. Related: Consolidating (1660s).
pp. adj. from consolidate. Of money, debt, etc., from 1753; in lit. sense of "made firm, unified," from c.1850.