To sign on the opposite side of (a document).
To add a second signature to a document, affirming the validity of the signature of another person.
A second signature added to a document to affirm the validity of the signature of the first person.
The response to a sign or signal.
To write or cut (words) onto (something, especially a hard surface, or a book to be given to another person); to engrave.
To draw a circle, sphere, etc. inside a polygon, polyhedron, etc. and tangent to all its sides.