From The Collaborative International Dictionary of English v.0.48:
Tart \Tart\, a. [AS. teart. [root]63. Cf. Tear, v. t.]
1. Sharp to the taste; acid; sour; as, a tart apple.
[1913 Webster]
2. Fig.: Sharp; keen; severe; as, a tart reply; tart
language; a tart rebuke.
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Why art thou tart, my brother? --Bunyan.
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From The Collaborative International Dictionary of English v.0.48:
Tart \Tart\, n. [OE. tarte, F. tarte; perhaps originally the
same word as tourte, LL. torta, fr. L. tortus, p. p. of
torquere to twist, bend, wind, because tarts were originally
made of a twisted shape. Cf. Torture, n.]
A species of small open pie, or piece of pastry, containing
jelly or conserve; a sort of fruit pie.
[1913 Webster]