adverb
almost, nearly
A2
fast is an adverb meaning 'almost' or 'nearly'. It's a degree adverb used before numbers, adjectives or verbs (e.g., almost finished). Not a verb; no auxiliary. Do not confuse with English 'fast' meaning 'quick'. It modifies extent: fast zehn, fast immer, fast fertig.
Examples
Der Bus verpasste fast die Haltestelle, weil der Fahrer zu spät bremste.
The bus almost missed the stop because the driver braked too late.
Es ist fast neun Uhr.
It's almost nine o'clock.
Ich habe es fast geschafft.
I nearly made it.
Details
Mnemonics
Imagine a progress bar that is almost full with the label 'fast' above it — it's nearly finished.
Sounds like the English word 'fast' — but in German think 'almost' or 'nearly'.
Notes
In German, 'fast' usually means 'almost' or 'nearly'. Don't confuse it with the English adjective 'fast' (quick).