blank
n. countablen. an empty space on a piece of paper or a screen where you are supposed to write something. It can also mean a moment when you suddenly forget what you were going to say.
n. an empty space or gap in a document intended to be filled with information; also refers to a sudden failure of memory or a cartridge containing gunpowder but no bullet.
Please write your name in the blank at the top of the page.
I knew the answer a minute ago, but my mind went completely blank when the teacher asked me.
The witness stared at the blank for several seconds before realizing the form required a signature rather than a printed name to be legally binding.
Often used in the phrase 'draw a blank' to describe a failure to remember or find something.
I have a blank in my mindMy mind went blankLearners often use 'blank' as a noun for a memory lapse, but the standard idiomatic expression uses 'blank' as an adjective with the verb 'go'.