British present participle of garrotte; the act of executing or killing by garroting using British spelling.
From garrotte plus -ing using British spelling conventions. The double-t before -ing is typical of British English doubling rules.
British English loves doubling consonants before suffixes—compare 'garroting' (American, one t) with 'garrotting' (British, two t's). The same rule gives us 'travelling' (British) versus 'traveling' (American)!
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