al·low / əˈlou/ • v. [tr.] 1. admit (an event or activity) as legal or acceptable: a plan to allow Sunday shopping. ∎  give (someone) permission to do something: the dissident was allowed to leave the country. ∎  permit (someone) to have (something): he was allowed his first sip of Scotch. ∎  permit (someone) to enter a place or go in a particular direction: the river was patrolled and few people were allowed across. ∎  fail to prevent (something) from happening: I could not believe that we would allow the opportunity to slip away.2. give the necessary time or opportunity for: he stopped for a moment to allow his eyes to adjust. ∎  [intr.] (allow for) make provision or provide scope for (something): the house was demolished to allow for road widening. ∎  [intr.] (allow for) take (something) into consideration when making plans or calculations: income rose by 11 percent allowing for inflation. ∎  provide or set aside (a specified amount of something) for a specific purpose: allow an hour or so for driving.3. admit the truth of; concede: he allowed that the penalty appeared too harsh for the crime. ∎ inf. or dial. assert; be of the opinion: Lincoln allowed that he himself could never support the man.DERIVATIVES: al·low·a·ble adj.al·low·a·bly / -əblē/ adv.

allow
A. †commend; admit, permit;

B. assign, allot. XIV. — OF. alouer, later all- :- (i) L. allaudāre, f. AL-1 + laudāre praise, LAUD, (ii) medL. allocāre place, ALLOCATE. The phonetic identification in OF. of the orig. distinct forms involved semantic conflation in which the two main senses were blended, e.g. assign with approval, grant, concede, permit.
So allowable, allowance XIV.