نون ثقيلة

The نون ثقيلة refers to the heavy emphatic nūn (نَّ) in Arabic grammar. It is a suffix used to emphasize verbs, making them more forceful and assertive. Unlike the light emphatic nūn (نْ), the heavy emphatic nūn is stressed and follows a closed syllable, such as in the example لَتَكْتُبَنَّ (you will surely write).