superscribe

1. To write on the outside or upper part of (a letter, for example).
2. To write (a name or an address, for example) on the top or outside.

[Latin superscrībere, to write over : super-, super- + scrībere, to write.]

verb

To mark (a written communication) with its destination: address, direct. See start/end.

The verb has 2 meanings:

Meaning #1: write on the top or outside

Meaning #2: write on the outside or upper part of