irregularity

US /ɪˌreɡ.jəˈler.ə.t̬i/
UK /ɪˌreɡ.jəˈler.ə.t̬i/
1.

sự bất thường

the quality of not being regular in shape or form, or an example of this:

:
The pictures showed cracks and other irregularities in otherwise perfectly regular crystals.