O.E. scrifan "assign, decree, impose penance," from W.Gmc. *skriban (cf. O.S. scriban, O.Du. scrivan, Du. schrijven "to write;" O.N. skrjpt "penance, confession"), an early borrowing from L. scribere "to write" (see script).
1570s, shortened from Shrovetide (early 15c.), from schrof-, related to schrifen (see shrive). Shrove Tuesday (c.1500) is from practice of celebration and merrymaking before going to confession at the beginning of Lent.