linguistics - Verbal analogy: sweet _ness_ is to suffix as boat _swain_ is to ... In other words, what is the term for the _swain_ morpheme?

At some point in the past I encountered the following verbal analogy:

SWEET NESS : SUFFIX :: BOAT SWAIN : ?

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In my view, the question is asking what one would term the "swain" morpheme in "boatswain".

I have ruled out suffix itself as "swain" is neither an inflectional nor (appears to be) a derivational ending.

Some answers I have found and excluded are:

• suprafix/superfix : this pertains to the patterns of tone or stress on various parts of a word that may determine its meaning, e.g. to distinguish between the verb form of conduct from the noun form


• stem : would only work if you considered "boat" as a prefix

My best guess so far would be "root", in that the word "boatswain" consists of two roots -- "boat" and "swain" -- in a similar way to the word "wheelchair".

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What do the expert linguists among you think?