Observation

Senses relating to the observance of custom, duty, etc.

• 1. An action, esp. of a religious and ceremonial nature, performed in accordance with prescribed usage; a customary action, ceremony, or ritual; = OBSERVANCE n. 1. rare after 17th cent.

• 2. More generally: the action or practice of following or heeding a particular law, duty, etc.; adherence or regard to a particular custom, practice, principle, etc.; = OBSERVANCE n. 4a. Usu. with of. Now rare.

• 3. Regard, respect, deference; respectful or courteous attention. Cf. OBSERVANCE n. 5. Obs.

• 4. Attentive care, heed; = OBSERVANCE n. 3. Obs.

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Senses relating to observing or taking notice.

• 5. a. The action or an act of observing, watching, or noticing; the fact or condition of being watched or noticed; notice; perception.

b. Noteworthiness, notability. Usu. with modifying adjective in of {emem} observation. Obs.

c. The faculty or power of observation; the habit of observing, perceiving or taking notice. Now rare. Perh. Obs.

d. Attention to, or inspection of, omens; augury, divination; an instance of this. Obs.

e. Mil. The watching of an enemy's positions, movements, responses, etc.; reconnaissance (chiefly in compounds: see Compounds 1). army of observation n. a force employed in watching an enemy force. Similarly corps (etc.) of observation.

• 6. Observed truth or fact; something learned by observing; a rule or maxim gathered from experience.

• 7. a. The action or an act of observing scientifically; esp. the careful watching and noting of an object or phenomenon in regard to its cause or effect, or of objects or phenomena in regard to their mutual relations (contrasted with experiment). Also: a measurement or other piece of information so obtained; an experimental result.

b. spec. The measurement of the altitude of the sun (or other celestial object) by means of an astronomical instrument, in order to ascertain latitude or longitude; an instance of this. to work an observation: to ascertain the latitude or longitude by means of calculations based on a measurement of the sun's altitude.

• 8. As a mass noun: comment, animadversion. More usually as a count noun: a remark, statement, or comment prompted by something seen, heard, or noticed.

• 9. An object of attention. Obs. rare.

Phrases

• under observation.

a. Being watched closely or systematically; (being, becoming, or kept) subject to close scrutiny or monitoring, spec. as the object of scientific study under experimental or natural conditions. Cf. sense 7a, UNDER prep. 13c.

b. Of a suspect, enemy, etc., or a location: (being kept) under surveillance, esp. as part of a criminal investigation or military campaign.

c. Med. Of a patient, esp. one kept in hospital: (being, kept, or becoming) subject to close scrutiny or monitoring as to the symptoms, progress, etc., of a medical condition, esp. pending diagnosis or as an aid to prescribing an appropriate treatment.