Repellency refers to the ability of a substance or object to repel or resist something, such as water or insects. There are several synonyms for this word that can be used interchangeably, including resistance, nonstick, nonabsorbent, impermeable, and deterrent. These words all describe the ability of something to prevent the penetration or absorption of another substance. Additionally, repellency can also be described as being antipathetic, forbidding, or unwelcoming. These synonyms emphasize the negative or unwelcoming nature of the substance or object that is being repelled by the repellent. It is important to choose the right synonym depending on the context and emphasis needed in the sentence or phrase.