younger brother; junior male; I (modest word in letter)
Pictograph of a rope neatly wrapped around a weapon handle. Based on the original meaning "orderly". The meaning later shifted to "next in sequence" (now written as 第) and "younger brother".
《說文》：“弟，韋束之次弟也。从古字之象。，古文弟，从古文韋省，丿聲。”
order