surskribo

A real build, and you can hear every piece. Sur is on. Skribi is to write. -o makes it a noun. Surskribo is a written-on-thing: the lettering cut into a gravestone, painted on a wall, struck on a coin, printed across a label. The sur is the ordinary preposition you already use twenty times a day, doing its ordinary job at the front of a compound.

The skribi family, which is worth learning as a family.

• Subskribi, write-under: to sign.
• Priskribi, write-about: to describe.
• Enskribi, write-in: to enrol, to enter in a register.
• Transskribi, write-across: to transcribe. Note both s, one from trans and one from skribi.
• Surskribo, write-on: the inscription.

Every one of those is a preposition you know plus a verb you know, and the meanings are the sum of the parts.

And now the one that is not in the family. Preskribi, to prescribe, arrives one band earlier in this same tier and looks like it belongs on that list. It does not. Esperanto has no prefix pre-; its before is antaŭ-. So preskrib- is a single root borrowed whole from the international word, and cutting it at the seam you can see gets you pres- plus skribi, print-write, which is not what a doctor does. The sibling page carries the same warning. The general principle is in the compounding article: a compound is only a compound if every piece is a live Esperanto morpheme.