<p><strong>Verb (used with object)</strong></p><ul><li>to see, watch, perceive, or notice: He observed the passersby in the street.</li><li>to regard with attention, especially so as to see or learn something: I want you to observe her reaction to the judge's question.</li><li>to watch, view, or note for a scientific, official, or other special purpose: to observe an eclipse.</li><li>to state by way of comment; remark: He observed frequently that clerks were not as courteous as they used to be.</li><li>to keep or maintain in one's action, conduct, etc.: You must observe quiet.</li><li>to obey, comply with, or conform to: to observe laws.</li><li>to show regard for by some appropriate procedure, ceremony, etc.: to observe Palm Sunday.</li><li>to perform duly or solemnize (ceremonies, rites, etc.).</li><li>to note or inspect closely for an omen or sign of future events.</li></ul><p><strong>Verb (used without object)</strong></p><ul><li>to notice.</li><li>to act as an observer.</li><li>to remark or comment (usually followed by on or upon).</li></ul>