may

American Heritage® Dictionary of the English Language, Fourth Edition

1. v. To be allowed or permitted to: May I take a swim? Yes, you may.
2. v. Used to indicate a certain measure of likelihood or possibility: It may rain this afternoon.
3. v. Used to express a desire or fervent wish: Long may he live!
4. v. Used to express contingency, purpose, or result in clauses introduced by that or so that: expressing ideas so that the average person may understand.
5. v. To be obliged; must. Used in statutes, deeds, and other legal documents. See Usage Note at can¹.
6. n. Chiefly British The blossoms of the hawthorn.

Century Dictionary and Cyclopedia

1. A. As an independent verb, or as a quasi-auxiliary: To have power; have ability; be able; can. In the absolute original use, ‘can,’ now rare (being superseded by can) except where a degree of contingency is involved, when the use passes insensibly into the later uses. The uses of may are much involved, the notions of power, ability, opportunity, permission, contingency, etc., passing into each other, and may in many constructions being purposely or inevitably used with more or less indefiniteness. The principal uses are as follows: To indicate subjective ability, or abstract possibility: rarely used absolutely (as in the first quotation), but usually with an infinitive (not, however, as a mere auxiliary). See also mow.
2. To indicate possibility with contingency.
3. In this sense, when a negative clause was followed by a contingent clause with if, may in the latter clause was formerly used elliptically, if I may meaning ‘if I can control it’ or ‘prevent it.’
4. Sometimes may is used merely to avoid a certain bluntness in putting a question, or to suggest doubt as to whether the person to whom the question is addressed will be able to answer it definitely.
5. The preterit might is similarly used, with some slight addition of contempt.
6. To indicate opportunity, moral power, or the absolute power residing in another agent.
7. In this sense may is scarcely used now in negative clauses, as permission refused amounts to an absolute prohibition, and accordingly removes all doubt or contingency.
8. To indicate desire, as in prayer, aspiration, imprecation, benediction, and the like. In this sense might is often used for a wish contrary to what can or must be: as, O that I might recall him from the grave !
9. In law, may in a statute is usually interpreted to mean must, when used not to confer a favor, but to impose a duty in the exercise of which the statute shows that the public or private persons are to be regarded as having an interest.
10. In conditional clauses. [Rare, except in clauses where permission is distinctly expressed.]
11. In concessive clauses.
12. In clauses expressing a purpose.
13. n. A kinsman.
14. n. A person.
15. n. A maiden; a virgin.
16. n. The fifth month of the year, consisting of thirty-one days, reckoned on the continent of Europe and in America as the last month of spring, but in Great Britain commonly as the first of summer.
17. n. Figuratively, the early part or springtime of life.
18. n. [lowercase] The hawthorn: so called because it blooms in May. Also May-bush.
19. n. Some other plant, especially species of Spiræa: as, Italian may.
20. n. The festivities or games of May-day.
21. n. In Cambridge University, England, the Easter-term examination.
22. To celebrate May-day; take part in the festivities of Mayday: chiefly or only in the verbal noun maying and the derivative mayer: as, to go a maying.

Wiktionary

1. n. The hawthorn bush or its blossoms.
2. v. To gather may.

GNU Webster's 1913

1. v. Ability, competency, or possibility; -- now oftener expressed by can.
2. v. Liberty; permission; allowance.
3. v. Contingency or liability; possibility or probability.
4. v. Modesty, courtesy, or concession, or a desire to soften a question or remark.
5. v. Desire or wish, as in prayer, imprecation, benediction, and the like.
6. n. obsolete A maiden.
7. n. The fifth month of the year, containing thirty-one days.
8. n. The early part or springtime of life.
9. n. (Bot.) The flowers of the hawthorn; -- so called from their time of blossoming; also, the hawthorn.
10. n. The merrymaking of May Day.

WordNet 3.0

1. n. thorny Eurasian shrub of small tree having dense clusters of white to scarlet flowers followed by deep red berries; established as an escape in eastern North America
2. n. the month following April and preceding June