allow (v.)

early 14c., allouen, "to commend, praise; approve of, be pleased with; appreciate the value of;" also, "take into account or give credit for," also, in law and philosophy, "recognize, admit as valid" (a privilege, an excuse, a statement, etc.). From late 14c. as "sanction or permit; condone;" in business use from early 15c.

The Middle English word is from Anglo-French alouer, Old French aloer, alloiier (13c.) "place, situate, arrange; allot, apportion, bestow, assign," from Latin allocare "allocate" (see allocate). This word in Old French was confused and ultimately merged with aloer; alloer "to praise, commend, approve," from Latin allaudare, adlaudare, compound of ad "to" (see ad-) + laudare "to praise" (see laud).

Between the two primary significations there naturally arose a variety of uses blending them in the general idea of assign with approval, grant, concede a thing claimed or urged, admit a thing offered, permit, etc., etc. [OED].

From the first word came the sense preserved in allowance "money granted;" from the second came allowance "permission based on approval." Meaning "assert, say," 19c. U.S. colloquial, also was in English dialect and goes back to 1570s. Related: Allowed; allowing.

Definitions of allow

allow (v.)
make it possible through a specific action or lack of action for something to happen;
This sealed door won't allow the water come into the basement
Synonyms: let / permit
allow (v.)
consent to, give permission;
I cannot allow you to see your exam
Synonyms: permit / let / countenance
allow (v.)
let have;
Mandela was allowed few visitors in prison
Synonyms: grant
allow (v.)
give or assign a resource to a particular person or cause;
Synonyms: appropriate / earmark / set aside / reserve
allow (v.)
make a possibility or provide opportunity for; permit to be attainable or cause to remain;
allow for mistakes
The evidence allows only one conclusion
Synonyms: leave / allow for / provide
allow (v.)
allow or plan for a certain possibility; concede the truth or validity of something;
I allow for this possibility
Synonyms: take into account
allow (v.)
afford possibility;
This short story allows of several different interpretations
Synonyms: admit
allow (v.)
allow the other (baseball) team to score;
Synonyms: give up
allow (v.)
grant as a discount or in exchange;
The camera store owner allowed me $50 on my old camera
allow (v.)
allow the presence of or allow (an activity) without opposing or prohibiting;
We don't allow dogs here
Synonyms: permit / tolerate