Nictate is an uncommon word, so finding synonyms for it can be challenging. Nictate means to blink or wink, so words like blink, flutter, twinkle and flicker can be used as synonyms. If you want to use a more formal tone, you could use words like bat or close and open the eyes. If you want to describe the action of nictating, words like quiver or pulsate might fit. Finally, in some contexts where nictate is used as a medical term to refer to a fast, involuntary blinking, words like spasm or tic could be used to describe the action.