• noun Mycology .a chemotactic substance, identical with cAMP, secreted bymyxamebas of cellular slime molds and attracting othermyxamebas to aggregate and form a pseudoplasmodium.Origin:

1945–50; < NL Acras ( iales ) an order of cellular slime molds (Acras ( is ) a genus, so named from the lack of fusion between thecells (< Gk; see a-6 , crasis) + -ales -ales) + -in2