deafness, deaf person, deafen
聾 centers on the inability to hear: deafness, a deaf person, or the act of making someone deaf. The meanings all revolve around a profound loss of hearing.
聾 combines 龍 (dragon) and 耳 (ear). The traditional explanation is that a dragon, despite its power, is deaf, so the character represents deafness. However, the exact historical development is uncertain, and the dragon component may have originally served a phonetic role.
A dragon (龍) with an ear (耳) that cannot hear. Even a mighty dragon can be deaf, so 聾 means deafness.
For ロウ, imagine a deaf dragon letting out a low, rumbling roar that it cannot hear itself: low roar -> ロウ.