Alternative forms 
Uncertain. Possibly from earlier polcher, which according to Walde-Hoffman and Pokorny reflects Proto-Indo-European *perḱ- (“motley, variegated”), with dissimilation *perḱ-ro-s > *pelḱ-ro-s. De Vaan rejects that connection as both irregular and semantically incompatible, and assigns no etymology.
pulcher m (feminine pulchra, neuter pulchrum); first/second declension
- beautiful, fair
- (figuratively) noble, honorable, excellent
- (substantive) beauty
Derived terms 
- Michiel de Vaan, Etymological Dictionary of Latin and the other Italic Languages, Brill, 2008, page 496