This paper has two main purposes; firstly, to ascertain the Korean indigenous morpheme of Sino-Korean word `梁`, and secondly, to grasp its meaning. Its indigenous morpheme is ascertained as `·돓`. It was alternated with /tok/~/to/ before Late Middle Korean period, which resembled that of `돓(stone)`. It could be thought that the two words had some original relationship with each other. Its meaning is understood as [a door] and [an important place or position]. This set of meaning belongs to one same semantic category. Furthermore, its meaning could be derived from that of a word `돓`, [stone]. Therefore, the four kinds of meaning, i.e. [stone], [a door], [an important place], and [gutter] belongs to one same semantic category. The above aspect of morphological similarity and semantic relation suggests the possibility of the lexical differentiation by tonemes before Middle Korean period.