malapropos

/ˌmælæprəˈpoʊ/
adjective
  1. Inappropriate or out of place in a given situation.
    • His malapropos joke about the weather fell flat at the funeral.
    • Wearing a swimsuit to a formal dinner is malapropos.
    • The comment was malapropos, coming right after the serious announcement.
Antonyms
adverb
  1. In an inappropriate or untimely manner.
    • The question was asked malapropos, just as everyone was leaving.
    • She arrived malapropos, interrupting the speaker mid-sentence.
    • He spoke malapropos, mentioning the surprise party while the guest of honor was nearby.