I have a single belief, but i believe in many things

I have a single knife, but at set of knives

The bud had a single leaf, but a tree has many leaves..

The general rule is f changes to ves as words become plural..

But what about motif as a theme-- a recurring salient thematic element, a floral motif would includes many floral elements.

But if I have a collections stamps (for stamp art) -- I have a set of florals, and a set of coffee related stamps, and a set of trees. Do i have several motifs? of several motives?

This web pages says motives-- Take a glance at the available motives.
http:// http://www.magical-stamping-tour.com/seite_4/seite_4.html

M-W10 says motives are something (as a need or desire) that causes a person to act. , 2) a recurrent phrase of figure that is developed throught the course of a musical composition., and finally :MOTIF

So which is right? and are there words where what appears to be the plural is a totally different word?


my other obsession