Unrecognizable means changed so completely that you can't identify or recognize something or someone anymore. When your older cousin returns from college with a completely different haircut, new glasses, and a growth spurt, you might say he's unrecognizable.

The word combines recognize (to identify something you've seen before) with the prefix un- (meaning “not”). Something unrecognizable has transformed so dramatically that familiar features have disappeared. After a fire, a building might be unrecognizable, reduced to charred ruins. A caterpillar becomes unrecognizable after transforming into a butterfly.

People use this word for dramatic changes. Your handwriting might be messy, but it's probably not unrecognizable. However, if you broke your writing hand and had to write with the other hand, your handwriting might truly be unrecognizable. The word suggests a change so complete that the connection to the original is nearly impossible to see.

Sometimes unrecognizable describes positive transformations: a neglected park restored to beauty might be unrecognizable in the best way. Other times it describes destruction or loss: photos damaged by water might become unrecognizable. The word captures that startling moment when you realize something familiar has become completely foreign.