Headmost and Prefatory

Headmost adjective - Coming before all others in time or order.

Prefatory and headmost are semantically related. In some cases you can use "Prefatory" instead an adjective "Headmost".

Prefatory adjective - Coming before the main part or item usually to introduce or prepare for what follows.

Headmost and prefatory are semantically related. Sometimes you can use "Headmost" instead an adjective "Prefatory".