XI

n. 14th letter of the Greek alphabet; number 11 (Roman Numerals)

Xi (uppercase Ξ, lowercase ξ) is the 14th letter of the Greek alphabet. It is pronounced by US English speakers, but is the correct Greek pronunciation. The Greek pronunciation has also become fairly common among mathematicians, even speaking in English. In the system of Greek numerals, it has a value of 60. Its Latin equivalent is X.
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11 (eleven) is the natural number following 10 and preceding 12. It is the first number which cannot be represented by a human counting his or her eight fingers and two thumbs additively (although it can be represented in a variety of other ways using human bodily parts, such as counting additively with the twenty digits including the toes, using the thumb to count the finger phalanges of one hand additively up to twelve, or using the fingers in one hand to count up to fifteen binarily). Eleven is the smallest positive integer requiring three syllables in English, and it is also the largest prime number with a single-morpheme name in this language (although etymologically the word eleven originated from a Germanic compound *ainlif meaning "one left" [1]).
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Noun
1. the cardinal number that is the sum of ten and one
(synonym) eleven, 11
(hypernym) large integer

Noun
1. the 14th letter of the Greek alphabet
(hypernym) letter, letter of the alphabet, alphabetic character
(member-holonym) Greek alphabet
Adjective
1. being one more than ten
(synonym) eleven, 11
(similar) cardinal

n. xi, 14th letter of the Greek alphabet; number 11 (Roman Numerals)

interj. gee, gosh!