The goal was disallowed because the player was offside.
Origin of disallow
Middle English disallowenfrom Old French desalouerto reprimanddes-dis-alouerto approveallow
American Heritage Dictionary of the English Language, 5th Edition
From Middle English, from Old French desalouer; synchronically analyzable as dis- + allow.
Disallow Sentence Examples
The king is given the power to disallow any law within a year of it having received the assent of the governorgeneral.
Any owner of property or ratepayer may attend the audit and object to the accounts, and either on such objection or on his own motion the auditor may disallow any payment and surcharge the amount on the persons who made or authorized it.
As a general rule our policy on alcohol is to disallow the taking of alcoholic refreshments whilst in the workplace.
Allow or disallow the ability to adjust the terrain regardless of impeding items like in-game objects, Sim characters, and other structures.