Apt/æpt/ Definition 1 of 4Pro Tip 1/3Expectations of Behavior Use 'apt' to express a future action seen as characteristic based on past behavior. He's apt to forget his keys. Pro Tip 2/3Subtle Probability 'Apt' indicates a good chance of something happening, but not certainty. Travelers are apt to face delays during the storm. Pro Tip 3/3Personal Tendency Use it to hint at someone's tendencies without being derogatory. Children are apt to be playful.