Eight hard words

I was humiliated in trying to make out the meaning of eight hard words. See how you do: claustration, edulcoration, eidolic, idoneous, infraction, straticulate, tergiversation, velleity.

The little list was included in his edition of Fowler’s Modern English Usage by the late R.W. Burchfield in 1996. He made the point that the first four of these Latinate words did not appear in the Concise Oxford Dictionary. Yet one man’s hard word is another man’s fodder for daily discourse. I wouldn’t count infraction as hard. But I failed on idoneous, which the Oxford English Dictionary (in 1899) called ‘now rare’. It means ‘fit, suitable’, as for public office, though Robert Boyle, the 17th-century scientist, used it of material suitable for producing saltpetre.