Is it ensure, insure, or assure?
Old English stream "a course of water," from Proto-Germanic *straumaz (cf. Old Saxon strom, Old Norse straumr, Danish strøm, Swedish ström, Norwegian straum, Old Frisian stram, Dutch stroom, Old High German stroum, German Strom "current, river"), from PIE root *sreu- "flow" (see rheum). Meaning "current in the sea" (e.g. Gulf Stream) is recorded from late 14c. Stream of consciousness in lit crit first recorded 1931, originally in psychology (1855).
early 13c., from stream (n.). Related: Streamed; streaming.
["STREAM: A Scheme Language for Formally Describing Digital Circuits", C.D. Kloos in PARLE: Parallel Architectures and Languages Europe, LNCS 259, Springer 1987].