So folks, in conclusion, based on info here
Singular: "lens" (British/American) or "lense" (American)
(imo, lens is more correct, but lense appears to be accepted in some circles as a variant as mentioned by blurblock).
Plural: "lenses"
Please do not ever ever use len :bsmilie:
Don't think any of us mean to be the language police, but if you want to talk photography, at least get the basic terms correct :sweatsm: