welcher meaning and definition in german
Determiner
Frequency: 
- interrogative which; what Welche Farbe hat dein Kleid? What colour is your dress? Welches Buch in diesem Regal hast du am öftesten gelesen? Which book on this shelf have you read most often?
- relative, literary which Er vergaß, die letzte Kugel aus dem Lauf zu nehmen, welcher Fehler ihn das Leben kosten würde. He forgot to remove the last bullet from the barrel, which mistake would cost him his life.
Pronoun
Frequency:
Welcher as a relative pronoun is virtually never used in the vernacular. It occurs more often in literary German, but overusing it is a typical trait of a pretentious style (generally corrected by editors). The normal relative pronoun in all registers of German is der and its forms. - interrogative which (one) Hier sind zwei Jacken, welche ist deine? There are two jackets here, which one is yours?
- relative, literary that; which; who; whom Der Mann, welchen sie als ihren Nachbarn erkannte, lag tot auf dem Bürgersteig. The man, whom she recognized to be her neighbour, was lying dead on the pavement.