Rule of construction meaning that where technical or legal words are used in a policy they are to be given their strict technical legal meaning unless the policy shows a different intention. Example: Four armed men stole cash from the insured. There was no other disturbance in the area, but technically there had been a ‘riot’ the definition of which (at that time) required only that there should be three persons with a common purpose threatening violence. The exclusion of ‘riot’ applied.