IPA: //ˈtiːspuːn//
KK: /ˈtiːspuːn/
A small spoon used for measuring or serving food, especially in cooking and for drinks like tea and coffee.
She added a teaspoon of sugar to her tea.
Teaspoon is formed from "tea" (from the Chinese word "t'e" or "cha", meaning a beverage made from the leaves of the tea plant) and "spoon" (from Old English "spōn", meaning a utensil for eating or serving). The word "teaspoon" refers to a small spoon specifically used for stirring or measuring tea.
Think of a small utensil ('spoon') used for a specific beverage ('tea') — that's how a teaspoon is defined.