This is the 289th most frequent Hungarian word.
mely
The Hungarian word "mely" means "which" or "that" (relative pronoun) or "deep" (adjective) depending on context.
Here, 'mely' is being used as an interrogative pronoun meaning 'which'.
Mely könyvet olvastad el a héten?
Which book did you read this week?
In this sentence, 'mely' functions as a relative pronoun meaning 'which', introducing a relative clause.
A folyó, mely az égen tükröződik, csodás.
The river, which reflects the sky, is wonderful.
Here, 'mély', a homonym of 'mely', is an adjective meaning 'deep', showing a different usage of the word.