(1):

(n.) Servile attention; sycophancy.

(2):

(n.) The act or practice of observing or noticing with attention; a heeding or keeping with care; performance; - usually with a sense of strictness and fidelity; as, the observance of the Sabbath is general; the strict observance of duties.

(3):

(n.) An act, ceremony, or rite, as of worship or respect; especially, a customary act or service of attention; a form; a practice; a rite; a custom.