There have been several unexplained disappearances of children in the small town recently.

disappearances 是名词 disappearance 的复数形式，由动词 disappear（消失）加上名词后缀 -ance 构成，表示"消失的行为或状态"。 unexplained disappearances 指"原因不明的失踪事件"，强调这些失踪案件至今没有找到合理解释。