An entry that begins after sam has passed — the cycle turns first, then the phrase starts and works toward the next landmark. Atit ("gone past") marks that sam is already behind when the phrase begins. The complement of anagat, and equally a matter of exact counting.
Atit entries are common in gats and Kathak compositions, where a piece may begin on, say, the third matra by design. The skill is in making the delayed entry sound intended rather than late — which comes down to confidence of attack and a clean arrival at the next sam.