英语词源字典 - 在线词源网站

allow (v.)[allow 词源字典]: 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.) "allot, apportion, bestow, assign," from Latin allocare (see allocate). This word in Old French was confused and ultimately merged with aloer; alloer "to praise, commend," from Latin allaudare, adlaudare, compound of ad- "to" (see ad-) + laudare "to praise" (see laud). From the first word came the sense preserved in allowance as "money granted;" from the second came its meaning "permission based on approval."
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].
Related: Allowed; allowing.[allow etymology, allow origin, 英语词源]
macadam (n.): 1824, named for inventor, Scottish civil engineer John L. McAdam (1756-1836), who developed a method of leveling roads and paving them with gravel and outlined the process in his pamphlet "Remarks on the Present System of Road-Making" (1822). Originally the word meant road material consisting of a solid mass of stones of nearly uniform size laid down in layers (McAdam did not approve of the use of binding materials or rollers). The idea of mixing tar with the gravel began 1880s.