to identify as something or someone previously seen, known, etc.

He had changed so much that one could scarcely recognize him.

to identify from knowledge of appearance or characteristics

I recognized him from the description. They recognized him as a fraud.

to perceive as existing or true; realize

to be the first to recognize a fact.

to acknowledge as the person entitled to speak at a particular time

The Speaker recognized the Congressman from Maine.

to acknowledge formally as entitled to treatment as a political unit

The United States promptly recognized Israel.

to acknowledge or accept formally a specified factual or legal situation

to recognize a successful revolutionary regime as the de facto government of the country.

to acknowledge or treat as valid

to recognize a claim.

to acknowledge acquaintance with, as by a greeting, handshake, etc.

to show appreciation of (achievement, service, merit, etc.), as by some reward, public honor, or the like.

Law . to acknowledge (an illegitimate child) as one's own.

Biochemistry, Immunology . to bind with, cleave, or otherwise react to (another substance) as a result of fitting its molecular shape or a portion of its shape.