A stated comparison (usually formed with “like” or “as”) between two fundamentally dissimilar things that have certain qualities in common.

Examples:

“The harpsichord sounds like two skeletons copulating on a corrugated tin roof.”

(Sir Thomas Beecham)

“Old friendships are like meats served up repeatedly, cold, comfortless, and distasteful. The stomach turns against them.”

(William Hazlitt)

“Life is like an onion: You peel it off one layer at a time, and sometimes you weep.”

(Carl Sandburg)

“He looked about as inconspicuous as a tarantula on a slice of angel food.”

(Raymond Chandler)

“Good coffee is like friendship: rich and warm and strong.”

(slogan of Pan-American Coffee Bureau, 1961)

“Life is rather like a tin of sardines: we’re all of us looking for the key.”

(Alan Bennett)

Her love radiated like the heat from the sun.