Listen dude, there’s exactly one source (dictionary.com) that even has that definition and it’s an even more archaic one than the British slang, referring to an astronomical device ships used for navigating in the 17th century.
You’re not really strengthening your case here.
E: Also your previous argument about ‘maters’ being the plural form leads me to believe you’re just grasping at straws now, at least the slang word (which appears in most dictionaries) had entries for the plural form on multiple sources.
Listen dude, there’s exactly one source (dictionary.com) that even has that definition and it’s an even more archaic one than the British slang, referring to an astronomical device ships used for navigating in the 17th century.
You’re not really strengthening your case here.
E: Also your previous argument about ‘maters’ being the plural form leads me to believe you’re just grasping at straws now, at least the slang word (which appears in most dictionaries) had entries for the plural form on multiple sources.