An Etymological Dictionary of Astronomy and Astrophysics

1. To hinder or prevent the passage of. → stopping power.
   

2. The diaphragm used in optical instruments to cut off the marginal portions of a beam of light passing through lenses. → field stop; → stop number.

Etymology (EN): M.E. stoppen (v.), O.E. -stoppian (in forstoppian “to stop up, stifle”); V.L. *stuppare “to stop or stuff with tow or oakum” (cf. It. stoppare, Fr. étouper “to stop with tow”), from L. stuppa “coarse part of flax, tow.”

Etymology (PE): 1) Bâzdâštan, bâzdâšt- “to stop, restrain, inhibit, coerce, detain,” from bâz-, → re-, + dâštan “to have, hold, maintain, possess,” → access.

2. Daricé, literally “small door; window,” from dar “door,” + -cé diminutive suffix. Dar “door,” Mid.Pers. dar, O.Pers. duvara-, Av. dvar-, cf. Skt. dvár-, Gk. thura, L. fores, P.Gmc. *dur-,
   O.E. duru, E. door, Lith. dvaras “court-yard;” PIE *dhwer-/*dhwor- “door, gate.”