WordNet sense 1 (conform one's action or practice to):

keep

WordNet sense 2 (celebrate, as of holidays or rites):

celebrate

WordNet sense 3 (show respect towards):

honor, respect, honour, abide by

WordNet sense 4 (follow with the eyes or the mind):

follow, watch, keep an eye on, watch over

WordNet sense 5 (discover or determine the existence, presence, or fact of):

discover, find, notice, detect

WordNet sense 6 (observe with care or pay close attention to):

note, take note

WordNet sense 7 (make mention of):

mention, remark

WordNet sense 8 (observe correctly or closely):

maintain