【Lack】 ,  【want】 ,  【dearth】 ,  【absence】 ,  【defect】 ,  【privation】  are comparable when denoting the fact or state of being without something.

【Lack】 is somewhat ambiguous in scope since it may imply either a total or a partial failure of something that in the circumstances might be expected to be present and often requires qualification to make its intent unequivocal.

【Want】  (see also POVERTY ) may imply either a partial or a complete 【lack】 but its range of application is far narrower than that of  【lack】  since it specifically applies to deficiencies of what is essential or at least needed or desirable; thus, one may exhibit either a  【want】  or a  【lack】  of tact; there may be a complete  【lack】  , rather than  【want】 , of pain immediately after some injuries.

【Dearth】 implies an often distressingly inadequate supply rather than a complete 【lack】 .

【Absence】 is perhaps the most unequivocal of these terms; when not qualified it denotes the complete 【lack】 of something or that something or occasionally someone is not present.

【Defect】  (see also BLEMISH ) implies the 【absence】 or 【lack】 of something required for completeness (as in form) or effectiveness (as in function).

【Privation】  in the sense pertinent here (see also POVERTY ) is used primarily in certain philosophical definitions of negative qualities or states as absences of the corresponding positives.