Note 141 — Chapter XIV · ON THE DIFFERENTIATION OF MEANING.

Shoal, the substantive from A.S. scólu, meaning either ‘a school’ or ‘a multitude’ (see Skeat, s.v.), seems to have been used convertibly with school, and indeed, the meaning of shoal has survived in the fisherman’s phrase a ‘school of mackerel;’ while the adjectives shoal and shallow likewise had the same meanings; but they have become so far differentiated that the latter form alone can be employed metaphorically; as when we say, ‘a man of shallow intellect.’