1. To put one's unique signature or official seal on something, especially a document, to indicate one's endorsement or approval. The chancellor refused to put his seal on any treaty that did not include financial aid for his country. Be sure to look over the fine print of the agreement before you put your seal on it.

2. To do or produce something in a way that demonstrates one's unique style, influence, or interpretation. Though he only produced the film, it's clear that the auteur director put his seal on it. The new CEO has made it clear she intends to put her own seal on the company. The novel is the author's attempt to put his seal on Shakespeare's Hamlet.