nighty
Nighty (phrase) means an informal shortening of "nighty night," used as a casual way of saying good night. Example: “Nighty, see you in the morning!”
How to use nighty
Learner’s notesIn plain EnglishA cutesy, informal way to say good night, or an alternate spelling of "nightie."
Very informal, often used with children.
Fill the gap
Can you complete this real example?
_____, see you in the morning!
Etymology
From night + -y, a playful diminutive suffix used in casual speech.