commando
Pronunciation: /kəˈmɑːndəʊ/
noun ( plural commandos)

Origin:
late 18th century (denoting a militia, originally consisting of Boers in South Africa): from Portuguese (earlier form of comando), from commandar 'to command', from late Latin commandare (see command)

Spelling rule
The plural of commando is made in the usual way, by adding -s: