ap·ti·tude (ăptĭ-td′, -tyd′)
1. An inherent ability, as for learning; a talent: an aptitude for mathematics.
2. Archaic The condition or quality of being suitable; appropriateness.
[Middle English, tendency, from Late Latin aptitūdō, aptitude, from Latin aptus, apt; see APT.]
ap′ti·tudi·nal (-tdn-əl, -tyd-) adj.
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Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.