estimated time of arrival.
abbreviation of estimated time (of) arrival, first attested 1939.
- Eta abstraction
[ey-tuh, ee-tuh] /ˈeɪ tə, ˈi tə/ noun, (used with a plural verb) Astronomy. 1. See under . [ak-wuh-rids, ah-kwuh-] /ˈæk wə rɪds, ˈɑ kwə-/ noun, (used with a plural verb) 1. either of two collections of meteors comprising meteor showers having their apparent origin in the constellation and visible either in early May (Eta Aquarids) […]
noun 1. a star and its surrounding nebula in the constellation Carina: the star was brighter than every star except Sirius in the 1840s and now is of seventh magnitude; the nebula is the brightest infrared object in the nighttime sky.
- Eta-c meson
[ey-tuh-see, ee-tuh-] /ˈeɪ təˈsi, ˈi tə-/ noun, Physics. 1. a neutral meson having a mass 5832 times that of the electron and a mean lifetime of approximately 3.1 × 10 -22 seconds.