umbra recta

短语

发音

UK /ˈʌmbɹə ˈɹɛktə/

释义与例句

n.
  1. 1.

    On a shadow in the shape of a right triangle, the length of the shadow's edge adjacent to a measured angle.

词源

First attested in Modern English in 1688, although the phrase was also used in Middle English by Geoffrey Chaucer (c. 1343–1400) in his Treatise on the Astrolabe; Latin: umbra (“shadow”) + rēcta (feminine nominative singular of rēctus, “straight”) = “straight shadow”; compare umbra versa.

来源：wiktionary