Entry 3 senses Webster, 1913

Setback

/(sĕt"băk`)/ · Set·back · IPA /ˈsɛtbæk/

01 n. Offset, n., 4.

1.
Offset, n., 4.(Arch.) See: Offset
2.
A backset; a countercurrent; an eddy.[U. S.]
3.
A reversal of progress in an endeavor; a reverse; a backset; a check; a repulse; a relapse.[Colloq. U.S.]