The odd name comes from 1940's slang. It was common in the UK and amoung the allies to add the letter 'O' at the end of a word. Hence Combato and Defendo, both styles of fighting taught to service men and women before going over. There is sufficient evidence out there to see the evolution of these styles through the war, and how the techniques changed as men returned from the battlefield with "This is what worked" stories.
Similar things go on in each war, anyone see the recent US Army Combatives championships?