umbra recta

== English == === Etymology === 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. === Pronunciation === (Received Pronunciation) enPR: ŭmʹbrə rĕkʹtə, IPA(key): /ˈʌmbɹə ˈɹɛktə/ === Noun === umbra recta On a shadow in the shape of a right triangle, the length of the shadow's edge adjacent to a measured angle. ==== Synonyms ==== umbra extensa