Synonyms for Sleek (same or very similar meaning)
WordNet sense 1 (designed or arranged to offer the least resistant to fluid flow):
aerodynamic, flowing, streamlinedWordNet sense 2 (having a smooth, gleaming surface):
glossy, satiny, silken, silky, slick, silklikeWordNet sense 3 (having a surface free from roughness or bumps or ridges or irregularities):
smoothFrom the ODE community, based on WordNetadd/edit