Why is the ninth month called September?
late 15c., "fountain, stream," probably from Middle French sourge-, stem of sourdre "to rise, swell," from Latin surgere "to rise," contraction of surrigere "to rise," from sub "up from below" + regere "to keep straight, guide" (see regal). Meaning "high, rolling swell of water" is from 1520s; figurative sense of "excited rising up" (as of feelings) is from 1510s.
1510s, from surge (n.). Related: Surged; surging.
Sorter, Updater, Report Generator, Etc. IBM 704, 1959. Sammet 1969, p.8.