Definition of "glitchy"

The output of a multiplexer can also be glitchy due to the propagation of glitches from the data and select inputs.

1996, IEEE/ACM International Conference on Computer-Aided Design: 1996 : November 10-14, 1996, San Jose, CA : Digest of Technical Papers, IEEE Computer Society

If the phone is still glitchy, try to remember what changes you made to it recently. Did you install some new App Store program, add a new video, mess around with your calendar?

2012, David Pogue, iPhone: The Missing Manual, "O'Reilly Media, Inc.", page 510