In telecommunications, a Slip
is defined as follows: In a sequence
of transmitted symbols, e.g., digital
bits, a signal phase shift
a signal positional displacement, that causes the loss of one or more symbols or the insertion of one or more extraneous symbols.
Note: Slips are usually caused by inadequate synchronization of the two clocks controlling the transmission and reception of the signals that represent the symbols.
Source: from Federal Standard 1037C
In the field of clothing a slip is a woman's underskirt, worn to help a dress or skirt hang smoothly.