deviation

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

• noun The act of deviating or turning aside.
• noun An instance of this.
• noun Divergence from an accepted idea, policy, or norm of behavior.
• noun An instance of this; an abnormality or departure from a norm.
• noun Deflection of a compass needle caused by local magnetic influence, especially on a ship.
• noun Statistics The difference, especially the absolute difference, between one number in a set of data and the mean of that set of data.

from The Century Dictionary.

• noun If the law of error be stated by the equation , more conveniently written , then is called by Pearson the standard deviation. The square root of the average of the squared departures from the mean in both directions is a measure of variability called the standard deviation.
• noun The act of deviating; a turning aside from the way or course.
• noun Departure from a certain standard or from a rule of conduct, an original plan, etc.; variation; specifically, obliquity of conduct.
• noun In com., the voluntary departure of a ship without necessity, or without reasonable cause, from the regular and usual course of the specific voyage insured.
• noun In astronomy, the oscillatory motion of a plane; especially, in the Ptolemaic system, the oscillation of the plane of the orbit of a planet, which was supposed to account for certain inequalities in the latitude.

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

• noun The act of deviating; a wandering from the way; variation from the common way, from an established rule, etc.; departure, as from the right course or the path of duty.
• noun The state or result of having deviated; a transgression; an act of sin; an error; an offense.
• noun (Com.) The voluntary and unnecessary departure of a ship from, or delay in, the regular and usual course of the specific voyage insured, thus releasing the underwriters from their responsibility.
• noun (Statistics, Physics) the difference between an expected value of an observation or measurement and the actual value.
• noun (Physics) that deviation from a strictly vertical line of descent which occurs in a body falling freely, in consequence of the rotation of the earth.
• noun the angle which the needle of a ship's compass makes with the magnetic meridian by reason of the magnetism of the iron parts of the ship.
• noun the difference between the actual direction of a plumb line and the direction it would have if the earth were a perfect ellipsoid and homogeneous, -- caused by the attraction of a mountain, or irregularities in the earth's density.

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

• noun The act of deviating; a wandering from the way; variation from the common way, from an established rule, etc.; departure, as from the right course or the path of duty.
• noun The state or result of having deviated; a transgression; an act of sin; an error; an offense.
• noun contract law The voluntary and unnecessary departure of a ship from, or delay in, the regular and usual course of the specific voyage insured, thus releasing the underwriters from their responsibility.
• noun Absolute Deviation The shortest distance between the center of the target and the point where a projectile hits or bursts.
• noun statistics For interval variables and ratio variables, a measure of difference between the observed value and the mean.
• noun metrology The signed difference between a value and its reference value.

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

• noun a turning aside (of your course or attention or concern)
• noun the difference between an observed value and the expected value of a variable or function
• noun deviate behavior
• noun the error of a compass due to local magnetic disturbances
• noun a variation that deviates from the standard or norm