observation

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The act of observing.
• noun The power or faculty of observing.
• noun The fact of being observed.
• noun The act or process of perceiving something, such as a phenomenon, often by means of an instrument, and making a record of the resulting information.
• noun The result or record of such an act or process.
• noun An inference, judgment, or remark that is made by observing.

from The Century Dictionary.

• noun The act or fact of observing, and noting or fixing in the mind; a seeing and noting; notice: as, a fact that does not come under one's observation.
• noun The habit or power of observing and noting: as, a man of great observation.
• noun An act of scientific observing; an accurate remarking (often with measurement) of a fact directly presented to the senses, together with the conditions under which it is presented: as, a meridian observation, made by a navigator, in which he measures the sun's altitude when on the meridian for the purpose of calculating the latitude; the meteorological observations made by the Signal Service Bureau.
• noun The result of such a scientific practice; the information gained by observing: as, to tabulate observations.
• noun Knowledge; experience.
• noun A remark, especially a remark based or professing to be based on what has been observed; an opinion expressed.
• noun The fact of being seen or noticed; notice; remark: as, to escape observation; anxious to avoid observation.
• noun Observance; careful attention to rule, custom, or precept, and performance of whatever is prescribed or required.
• noun A rite; a ceremony; an observance.
• noun Synonyms Observance, Observation. See observance.
• noun Experiment, etc. See experience.
• noun Note, Comment, etc. (see remark, n.), annotation.

from the GNU version of the Collaborative International Dictionary of English.

• noun The act or the faculty of observing or taking notice; the act of seeing, or of fixing the mind upon, anything.
• noun The result of an act, or of acts, of observing; view; reflection; conclusion; judgment.
• noun An expression of an opinion or judgment upon what one has observed; a remark.
• noun obsolete Performance of what is prescribed; adherence in practice; observance.
• noun The act of recognizing and noting some fact or occurrence in nature, as an aurora, a corona, or the structure of an animal.
• noun Specifically, the act of measuring, with suitable instruments, some magnitude, as the time of an occultation, with a clock; the right ascension of a star, with a transit instrument and clock; the sun's altitude, or the distance of the moon from a star, with a sextant; the temperature, with a thermometer, etc.
• noun The information so acquired.
• noun (Naut.) to ascertain the altitude of a heavenly body, with a view to fixing a vessel's position at sea.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The act of observing, and the fact of being observed.
• noun The act of noting and recording some event; or the record of such noting.
• noun A remark or comment.
• noun A judgement based on observing.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the act of observing; taking a patient look
• noun the act of noticing or paying attention
• noun facts learned by observing
• noun the act of making and recording a measurement
• noun a remark expressing careful consideration