essential item
nounUK /ɪˈsɛnʃəl ˈaɪtəm/
US /ɪˈsɛnʃəl ˈaɪtəm/
An essential item is something you really need and cannot do without.
Water is an essential item for every living thing.
OTHER MEANINGS
2. A thing that is required for a particular activity or trip.
A flashlight is an essential item for camping.
3. A product people must buy no matter what, even when prices rise.
Bread and milk are essential items at the grocery store.
4. Something that is a key part of a plan or recipe.
Eggs are an essential item in this cake recipe.