SHEMONEH ESREH (Heb. שְׁמוֹנֶה עֶשְׂרֵה; lit. "eighteen"), popular name for the *Amidah prayer. The name stems from the fact that the weekday Amidah originally contained 18 benedictions (although today none of the various Amidot recited on different occasions consists of exactly 18 benedictions).
"Shemoneh Esreh." Encyclopaedia Judaica. . Encyclopedia.com. (November 14, 2018). https://www.encyclopedia.com/religion/encyclopedias-almanacs-transcripts-and-maps/shemoneh-esreh
"Shemoneh Esreh." Encyclopaedia Judaica. . Retrieved November 14, 2018 from Encyclopedia.com: https://www.encyclopedia.com/religion/encyclopedias-almanacs-transcripts-and-maps/shemoneh-esreh