These words all denote a deficiency or non-existence of something specified or implied. Lack is a general term which means a total or partial insufficiency.

• It was a lack of cash that prevented me from joining you at lunch today; A lack of bedding in the weekender meant that three of us had to sleep on the floor.

Although lack by itself can express a totality of deficiency, a qualifying adjective is often used with it to avoid any possibility of confusion: The young man displayed a complete lack of courtesy and tact in dealing with his employer. No confusion about total lack is possible when absence is used alone. Absence is the opposite of presence; it means non-existence: The absence of a chairman turned the meeting into a near riot. The difference between lack and absence is apparent when we contrast "a lack of sugar in her diet" with "an absence of sugar in her diet." The former suggests that there is some sugar in the diet but not enough; the latter implies that there is no sugar at all in the diet. Absence , of course, can also signify the state of being away. In the example cited, "the absence of chairman" denotes the non-existence of a chairman. If the phrase were "in the absence of the chairman," it would be obvious that a chairman existed but was away at the time under discussion.

Shortage is synonymous with lack in designating a partial insufficiency, but more than lack it suggests an insufficiency of some established, required or accustomed amount: There was a shortage of bottled beer last week because of a delivery strike. Shortage also means the amount by which something is deficient: The total shortage amounted to $500.

Dearth , in a sense no longer used, meant dearness or costliness. It came later to refer to the kind of lack or scarcity which makes something costly, especially food in time of famine. An extension of this sense gives dearth the meaning of a lack or scarcity of anything: a dearth of content in an essay; a dearth of oranges because of drought conditions; a dearth of parental affection and discipline.