Somewhat foul or somewhat inclined to be foul; slightly dirty or unpleasant in a way that's not completely extreme.
From 'foul' with the diminishing suffix '-ish,' which means 'somewhat' or 'having a quality of.' This suffix construction became productive in English to express lesser degrees of qualities.
The '-ish' suffix is wonderfully flexible in English—you can add it to almost any adjective to make it less extreme, creating words like 'reddish,' 'oldish,' and 'foulish' that suggest something is borderline or uncertain.
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