welcher

See also: Welcher

English

welch +‎ -er

welcher (plural welchers)

Chinese:
Mandarin: please add this translation if you can
Finnish: maksamatta jättäjä
French: please add this translation if you can
German: Spitzbube (de) m (dated), Gauner (de) m, Zechpreller (de) m, Schwindler (de) m
Russian: please add this translation if you can
Spanish: please add this translation if you can
Thai: please add this translation if you can

From Middle High German welich, from Old High German welih, wilih, from Proto-Germanic *hwilīkaz. Compare English which.

welcher

(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.

welcher

(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.

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.
Welcher and its forms may be used avoid a doubled word. For example
Das Lied, welches das Kind vortrug, wurde vor langer Zeit geschrieben.

avoids das das. The welches version would still not be preferred in general though.

German does not distinguish between restrictive and non-restrictive relative clauses and relies solely on context to determine which is meant. (See the usage notes at which.) Thus der and its forms are still preferred when English prefers "which":
Paul schenkt sein Auto, das noch neu ist, seiner Tochter.
Paul is giving his car, which is still new, to his daughter.