diservo

Two roots, no surprises. Dio is God and servi is to serve, so a diservo is a service to God: the organised, public act of worship, held at an appointed hour, led by somebody whose job it is. English divine service is the identical compound and church service is the everyday equivalent.

Three words that English lets you confuse. English says church for all three of these and lets context sort it out. Esperanto does not:

• Preĝejo is the building. Preĝi plus -ej-, the place-for suffix: a praying-place.
• Eklezio is the institution, the body of believers, the thing that has a history and a hierarchy.
• Diservo is the event. It starts, it lasts an hour, it ends.

So "we go to church on Sunday" is ni iras al la preĝejo, "the church opposed the law" is la eklezio kontraŭis la leĝon, and "the service was long" is la diservo estis longa. Pick the wrong one and the sentence still parses, which is what makes it worth learning as a set.

Coverage. Diservo is denominationally neutral and covers a Protestant service, an Orthodox liturgy and a synagogue service equally. The Catholic Mass specifically is meso, which is a separate root and not a kind of diservo in the vocabulary even though it plainly is one in fact. The compound says only that God is being served, and in public.