One who makes observations, monitors or takes notice / One who adheres or follows laws, guidelines, etc.

(transitive) To notice or view, especially carefully or with attention to detail. / (transitive) To follow or obey the custom, practice, or rules (especially of a religion).

(archaic) An observation (remark, comment or judgement).

simple past tense and past participle of observe / (of a holiday) Exceptionally celebrated on a date other than the usual date.

plural of observe

Third-person singular simple present indicative form of observe

plural of observer

(uncountable) The state of being observable / (countable) A measure of the extent to which something is observable

plural of observability

Obsolete form of observance.