Underweight

Underweight

Adjective · /ˌʌndəˈweɪt/ · below the expected, normal, or recommended weight

Definition

Underweight describes a person, animal, or object that weighs less than the expected, required, or medically recommended amount. In medicine, a person is clinically underweight when their Body Mass Index falls below 18.5. In logistics, an underweight parcel fails to meet the minimum weight requirement for a shipping tier. In manufacturing, an underweight product has been underfilled. In all contexts, underweight signals that something falls short of a weight standard that matters — either for health, commerce, or safety.

Origin

Underweight is a compound of under, from Old English under meaning below or insufficient, and weight, from Old English wiht, related to the verb wegan meaning to weigh or carry. The pairing is straightforward: under the weight. The word appeared in English by the late nineteenth century, coinciding with the emergence of clinical nutrition as a medical discipline and the standardisation of weights and measures in industrial trade. Before that, thin or slight were the everyday terms for a person lacking expected body mass.