Entry 1 sense Webster, 1913 Ichthyosis · Ich·thy·o·sis · IPA /ɪkθɪˈəʊsɪs/ 01 n. A disease in which the skin is thick, rough, and scaly; -- called also fishskin. 1. A disease in which the skin is thick, rough, and scaly; -- called also fishskin.(Med.) Also: fishskin