This is the 15581st most frequent German word.
weiser
"Weiser" in German means "wise man" or "sage."
In this sentence, 'weiser' is used as an adjective modifying the noun 'Lehrer' to describe the characteristic of wisdom possessed by him.
Der alte Mann war ein weiser Lehrer.
The old man was a wise teacher.
Here, 'weise' (from 'weiser') is employed as an adjective describing the manner or mode ('Weise') of his decision-making, emphasizing its thoughtful and well-considered nature.
Er entscheidet sich auf eine weise Weise.
He decides in a wise manner.
In this usage, 'Weisen' refers to a 'wise person' or sage, functioning as a noun derived from 'weise' or 'weiser' to denote someone who is characterized by wisdom.