means To make the spontaneous sounds and facial expressions that signal amusement, delight, or sometimes nervousness.

from From Old English hliehhan, a word built to imitate the sound itself — those breathy, gasping bursts. It shares deep Germanic roots with the German lachen and Dutch lachen, and that stubborn silent 'gh' is the ghost of a throaty consonant our ancestors once actually pronounced, scraped from the back of the mouth like a cough turned happy.