nutrient (n.)
"a nutritious substance," 1828, noun use of adjective (1640s) meaning "providing nourishment," from Latin nutrientem (nominative nutriens), present participle of nutrire "to nourish, suckle, feed," from PIE *nu-tri-, suffixed form (with feminine agent suffix) of *(s)nau- "to swim, flow, let flow," hence "to suckle," extended form of root *sna- "to swim."