Which word describes the action of dividing something into separate parts?

The word "asunder" accurately describes the action of dividing something into separate parts. It indicates a clear separation or disconnection between entities, suggesting that something has been torn, split, or broken into parts. The concept of division is central to the meaning of "asunder," and it often conveys a sense of distance or fragmentation resulting from that division.

In contrast, the other options do not relate to the idea of dividing. "Baneful" refers to something causing harm or ruin, "avow" means to openly declare or affirm something, and "bombast" pertains to high-sounding language with little meaning, often used to impress others. Thus, "asunder" is the term that most accurately captures the essence of separating into parts.