able

Etymology 1

From Middle English able, from Old Northern French able, variant of Old French abile, habile, from Latin habilis (“easily managed, held, or handled; apt; skillful”), from habeō (“have, possess”) + -ibilis. Broadly ousted the native Old English magan.

adj

1. Having the necessary powers or the needed resources to accomplish a task.
2. Free from constraints preventing completion of task; permitted to; not prevented from.
   I’ll see you as soon as I’m able.
   With that obstacle removed, I am now able to proceed with my plan.
   I’m only able to visit you when I have other work here.
   That cliff is able to be climbed.
3. Gifted with skill, intelligence, knowledge, or competence.
   The chairman was also an able sailor.
4. (law) Legally qualified or competent.
   He is able to practice law in six states.
5. (nautical) Capable of performing all the requisite duties; as an able seaman.
6. (obsolete, dialectal) Having the physical strength; robust; healthy.
   After the past week of forced marches, only half the men are fully able.
7. (obsolete) Easy to use.
   As the hands are the most habil parts of the body... 1710, Thomas Betterton, The life of Mr. Thomas Betterton, the late eminent tragedian.
8. (obsolete) Suitable; competent.
   […] and for every able man servant that he or she shall carry or send armed and provided as aforesaid, ninety acres of land of like measure. 2006, Jon L. Wakelyn, America's Founding Charters: Primary Documents of Colonial and Revolutionary Era Governance, volume 1, Greenwood Publishing Group, page 212
9. (obsolete, dialectal) Liable to.
10. (obsolete) Rich; well-to-do.
    He was born to an able family.

Etymology 2

From Middle English ablen, from Middle English able (adjective).

verb

1. (transitive, obsolete) To make ready.
2. (transitive, obsolete) To make capable; to enable.
3. (transitive, obsolete) To dress.
4. (transitive, obsolete) To give power to; to reinforce; to confirm.
5. (transitive, obsolete) To vouch for; to guarantee.

Etymology 3

From the first letter of the word. Suggested in the 1916 United States Army Signal Book to distinguish the letter when communicating via telephone, and later adopted in other radio and telephone signal standards.

noun

1. (military) The letter "A" in Navy Phonetic Alphabet.