horaro

A collection of hours. That is genuinely what the word says. -Ar- is the suffix for the whole set of something: arbaro is a forest from arbo, vortaro is a dictionary from vorto, homaro is humanity from homo. Apply it to horo at rank 225 and you get the set of hours, arranged and written down, which is a timetable. English needed a compound of two nouns and a French borrowing (schedule, originally a strip of papyrus) to say the same thing. Esperanto used a suffix you already knew.

It covers everything English splits. A horaro is the train timetable, the school timetable, the opening hours of a shop, a conference programme, and your own day's plan. Labori laŭ horaro is to work to a schedule; horara is the adjective; senhorara describes the sort of week where nothing starts when it should. Where English distinguishes timetable from schedule from roster, Esperanto lets the context do it.

Do not confuse it with plano. A plano at 988 is what you intend to do; a horaro is when things happen. A train has a horaro and not a plano, and a battle has a plano and not a horaro. The near neighbours are tempo at 98 for time in general and programo at 1,219 for the content rather than the clock.