Let's get back to the original issue: should
seine become a common word? I'm not persuaded that it should.
The vast majority of examples of that sequence of letters are of course the name of the river, which is not eligible because of its capital
S. The next most common occurrence, in the Corpus of American English, seemed to be the German word for
his, in German passages quoted in English books and articles. The fishing/butterfly net meaning was the third most common, and that seemed to be concentrated in magazines like
National Parks,
Conservation and
National Geographic.
The word may be in your dictionary from schooldays, Les (although it was never clarified whether that was with a capital
S or not), but it's not included in quite a few "Advanced Learners" dictionaries, aimed at people learning English as a second language - like the
Cambridge Dictionary. The "3of6game" word list was compiled recently from 6 such dictionaries by the creator of the
12 Dicts package, Alan Beale. This list, which doesn't include
seine, is designed specifically to be used in word games based on common words. On the other hand, the word is found in the "2 of 12" list compiled from learners' dictionaries published in the US.
I need to be reasonably certain a word should be common before I classify it so. I'm not certain at all about
seine, so I'm leaving it as rare.
Just one thing I'm curious about - tpc, why do you try to remember which words are common and which rare? Don't you just play every word you know is a word?