Hypothenuse, the name of that side in a right-angled triangle which is opposite to the right angle. The well-known property of the hypothenuse, that the square described on it is equal to the sum of the squares described on the other two sides, is proved in the 47th proposition of the first book of Euclid's Elements:
Hypothenuse
Chambers's Encyclopaedia, Volume 6: Humber to Malta, p. 53
Source scan(s): p. 0062