An Etymological Dictionary of Astronomy and Astrophysics

To lessen the force, strength or intensity of something.

Etymology (EN): m M.E., from O.Fr. relaxer from L. relaxare “relax, loosen, open,” from → re- “back” + laxare “loosen,” from laxus “loose.”

Etymology (PE): Vâhelidan, from vâ-, → re-, +
helidan, heštan “to place, put” from Mid.Pers. hištan, hilidan “to let, set, leave, abandon;” Parthian Mid.Pers. hyrz; O.Pers. hard- “to send forth,” ava.hard- “to abandon;”
Av. harəz- “to discharge, send out; to filter,” hərəzaiti “releases, shoots;” cf. Skt. srj- “to let go or fly, throw, cast, emit, put forth;” Pali sajati “to let loose, send forth.”