1. adjective /ˈɹɛɡ.jə.lə(ɹ),ˈɹɛɡˌju.lə(ɹ),ˈɹɛɡjəlɚ/
The verb "to walk" is regular.
b) Normal; ordinary
The noun "mouse" has the irregular plural "mice".
2. noun /ˈɹɛɡ.jə.lə(ɹ),ˈɹɛɡˌju.lə(ɹ),ˈɹɛɡjəlɚ/
a) A member of the British Army (as opposed to a member of the Territorial Army or Reserve).
Bartenders usually know their regulars by name.
This gentleman was one of the architects regulars.
Wikipedia foundation.