- gradient (n.)
[gradient 词源字典]
- "steep slope of a road or railroad," 1835, principally in American English, probably from grade (n.) by analogy of quotient, etc. [OED]. It was used 17c. as an adjective, of animals, "characterized by walking;" in that case it is probably from Latin gradientem, present participle of gradi "to walk."[gradient etymology, gradient origin, 英语词源]