Mouse-ear \Mouse"-ear`\, n. (Bot.) (a) The forget-me-not ({Myosotis palustris}) and other species of the same genus. (b) A European species of hawkweed ({Hieracium Pilosella}). {Mouse-ear chickweed}, a name of two common species of chickweed ({Cerastium vulgarium}, and {C. viscosum}). {Mouse-ear cress}, a low cruciferous herb ({Sisymbrium Thaliana}). All these are low herbs with soft, oval, or obovate leaves, whence the name.