Origins
The English word 'depend' entered the language in the early fifteenth century, from Old French 'dependre,' which descended from Latin 'dependere' (to hang down, to hang from). The Latin verb combines 'de-' (down, from) and 'pendere' (to hang), creating the literal image of something suspended downward from a point of attachment.
The Latin verb 'pendere' is one of the most productive roots in the Romance languages and in English. It actually represents two related but distinct Latin verbs that merged in form: 'pendere' (intransitive, to hang) and 'pendere' (transitive, to weigh, to pay). Both trace back to the concept of suspension — weighing something meant suspending it from a balance. Paying someone meant weighing out metal (coins were weighed, not counted, in early economies). This dual nature — hanging and weighing — generated two vast families of English words.
The physical sense of 'depend' was the original one. In Latin, vines depended from trellises, hair depended from the head, ornaments depended from the neck. This meaning survived in English through the seventeenth century and beyond. John Milton wrote of leaves depending from branches in Paradise Lost. The architectural term 'dependent arch' (an arch that hangs from its supports rather than standing independently) preserves this physical sense.
Figurative Development
The figurative leap from 'hang from' to 'rely on' is intuitive. If you hang from something, that thing is your support — without it, you fall. To depend on someone is to be suspended from their support, their generosity, their reliability. The metaphor captures the vulnerability inherent in dependence: the dependent party is not standing on solid ground but hanging, and the person or thing depended upon could at any moment let go.
The noun 'dependence' (or 'dependency') entered English in the fifteenth century. 'Dependent' (the adjective and noun) followed shortly after. 'Independent' — formed with the Latin negative prefix 'in-' — appeared in the early seventeenth century and quickly became one of the most politically and philosophically charged words in English. The American Declaration of Independence (1776) is, etymologically, a declaration of no longer hanging from British support.
The word 'dependency' has specific meanings in several domains. In political science, a dependency is a territory that hangs from (is governed by) another state. In psychology and medicine, dependency describes a condition where a person cannot function without a substance or behavior — alcohol dependency, drug dependency. In software engineering, a dependency is a component that another component hangs from — cannot run without.
Later Development
The phrase 'it depends' has become one of the most common expressions in English, used to indicate that an answer is contingent on circumstances. Its ubiquity has worn away any sense of its etymological image, but the metaphor is still there: the answer hangs from conditions not yet specified.
The Latin root 'pendere' connects 'depend' to a remarkable constellation of English words. 'Suspend' (hang under, hang up), 'append' (hang onto), 'expend' (weigh out, pay out), 'impend' (hang over), 'pendant' (something that hangs), 'pendulum' (a hanging weight), 'pension' (a payment — from the weighing sense), 'ponder' (to weigh mentally), and even 'pound' (the unit of weight and currency) all descend from the same Latin verb. This family reveals how deeply the concepts of hanging, weighing, and paying were intertwined in the Roman mind — and remain so in English.
'Depend' sits at the emotional center of this family. Where 'pendant' and 'pendulum' are about physical hanging, and 'expend' and 'pension' are about weighing and paying, 'depend' captures the human condition of needing support — the existential vulnerability of being unable to stand alone.