An auxiliary verb characteristically used with other verbs to express mood, aspect, or tense. In English, the most common modal auxiliaries are can, could, may, might, must, ought, shall, should, will, and would. Also called modal.
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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.