Singular or plural?

44, or 46 if delimiting // count:

dr|wome|[aglx]e|et|ti|ia|[^u]s$|nn$|^.ic|^me

42 (or 44 with delimiters)

^.(e[^r]|ic)|x.|..me|ia|ti|.l..|nn$|[^u]s$ - Try it online!
^.(e[^r]|ic)|x.|..me|ia|[adjlu]...$|[^u]s$ - Try it online!