The word "沉溺" is formed by combining the character "沉", which means to sink or submerge, with the character "溺", which means to drown or be immersed. Both characters incorporate the water radical (氵), visually reinforcing the concept of being overwhelmed by liquid. Their semantic combination produces a metaphorical meaning of being deeply absorbed or engrossed in something, typically to an excessive or detrimental extent, hence conveying the sense of indulgence or addiction.