aikuchi
/ʌɪˈkʊtʃi/noun
A dagger or short sword manufactured without a hilt-guard, so that the hilt fits flush with the scabbard.
Origin
Late 19th century. From Japanese aikuchi, lit. ‘fitting the mouth’, so called on account of the snug fit between the hilt-collar and the opening of the scabbard in the absence of a guard.