"Ditziest" refers to a person who is scatterbrained, absent-minded, or flighty. Antonyms for this word would, therefore, describe someone who is the opposite - focused, deliberate, and intelligent. Words like "sharp," "smart," and "alert" all describe traits of someone who is not ditzy. Other antonyms for "ditziest" can include words like "attentive," "aware," "perceptive," and "informed." Using these antonyms helps to paint a picture of someone who is grounded, sensible, and thoughtful, rather than someone who is spacey and unorganized.