The quality or state of being foamy; the degree to which something is full of foam or has a frothy appearance.
From 'foam' + '-y' (adjective) + '-ness' (noun suffix converting qualities), creating an abstract noun describing the property or degree of foaminess.
The '-ness' suffix is one of the oldest and most versatile in English—it can attach to almost any adjective to create an abstract noun about that quality, which is why we have countless words like 'sadness,' 'kindness,' and 'foaminess.'
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