WordNet sense 1 (the phenomenon of a propagating wave (light or sound) being thrown back from a surface):

reflection

WordNet sense 2 (expression without words):

expression, manifestation

WordNet sense 3 (a remark expressing careful consideration):

observation

WordNet sense 4 (a calm lengthy intent consideration):

contemplation, musing, rumination, thoughtfulness

WordNet sense 5 (the ability to reflect beams or rays):

reflectivity

WordNet sense 6 (a likeness in which left and right are reversed):

mirror image