Learn Portuguese (Portugal): O comboio parte à meia-noite.

à is the contraction of the preposition a (at) and the feminine singular article a (the). While we use the plural às for most hours (like às duas horas for at two o'clock), meia-noite (midnight) and meio-dia (noon) are singular words, so they take the singular à (for midnight) or ao (for noon).

Why is it meia-noite instead of meio-noite?

It literally translates to half-night. Because the Portuguese word for night, noite, is a feminine noun, the word for half must match its gender. Therefore, we use the feminine meia instead of the masculine meio.

What verb does parte come from?

It comes from the verb partir. When talking about vehicles like a train (o comboio), it means to depart or to leave. It is a regular -ir verb, and parte is the he/she/it form used here for the train.

Do I always need to use a hyphen in meia-noite?

Yes! When you are talking about the specific time of midnight, meia-noite is always written as a single compound word connected by a hyphen.