n. The state of being double; doubleness.n. Doubleness of heart or speech; the acting or speaking differently in relation to the same thing at different times or to different persons, with intention to deceive; the practice of deception by means of dissimulation or double-dealing.n. In law, the pleading of two or more distinct matters together as if constituting but one.n. In biology, the division of a part of the body of an organism, such as a limb or a digit, into two equivalent parts which may be regarded as equivalent to normal single members.