The antonyms for the phrase "dropt a note" could be various depending on the context. Some possible antonyms could include: keeping silent, ignoring, forgetting, neglecting, failing to communicate, or not bothering to leave a message. Each of these antonyms suggests a lack of action or communication on the part of the speaker, indicating a failure to follow through with a task or to connect with someone. Instead of dropping a note, these antonyms suggest a lack of effort, communication, or attention, which could result in missed opportunities, misunderstandings, or damaged relationships.