Suppose we have two competitive synonyms A and B.
We found out that during the historical changes of the language, A gains dominant position. We found out the fact above via a statistical survey of language materials of different periods.
We think the reason that A gains dominant position is that there is a high-frequency word A' which has a similar form with A. (And, A, B and A' are roughly identical in meaning. Strict speaking, A and B are a bit stronger than A'.)
Which mechanism can be used to explain this?
I'm thinking of analogical mechanism.