An Etymological Dictionary of Astronomy and Astrophysics

To cause or allow something to continue for a long period of time.

Etymology (EN): M.E. suste(i)nen, from O.Fr. sustenir “hold up, endure,” from L. sustinere “hold up, support, endure,” from → sub- “up from below” + tenere “to hold,” from from PIE root *ten- “to stretch,” → tension.

Etymology (PE): Padârdan, from Sogd. padâr “to sustain, support,” from Proto-Ir. *pati-dar-, from *pati- “to, toward, in, at, agianst,” → ad hoc, + *dar “to hold, keep, maintain,” → property, + -dan infinitive suffix.