The antonyms for the word "brightenings" can be varied depending on the context. If it refers to the weather, the antonyms can be gloom, darkness, or stormy. If it refers to emotions, the antonyms can be sadness, depression, or distress. If it refers to light or colors, the antonyms can be dim, pale, or dull. Additionally, if it refers to a situation or a problem, the antonyms can be exacerbate, worsen, or complicate. Overall, the antonyms of "brightenings" represent a range of opposite conditions, emotions, and states that are diametrically opposed to the concept of brightness and positivity.