simile n.

"a comparison of two things in rhetoric or poetry," late 14c., from Latin simile "a like thing; a comparison, likeness, parallel," neuter of similis "like, resembling, of the same kind" (see similar). They must have notable points in common, both things must be mentioned, and the comparison should be directly stated. Further, to Johnson, "A simile, to be perfect, must both illustrate and ennoble the subject."