Medical Definition of naphthol
: either of two isomeric derivatives C10H8O of naphthalene found in coal tar or made synthetically:a: one used chiefly in synthesizing dyes—called also alpha-naphtholb: one used chiefly as an intermediate (as for dyes and pharmaceuticals) and especially formerly in medicine as an antiseptic and parasiticide—called also beta-naphthol
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