Origins
The word 'inhabitant' entered English in the fifteenth century from Old French, ultimately from Latin 'inhabitantem,' the present participle of 'inhabitāre' (to dwell in, to reside). The Latin verb is composed of 'in-' (in, within) and 'habitāre' (to dwell, to live in, to frequent), which is itself the frequentative form of 'habēre' (to have, to hold, to possess). The etymological chain reveals a beautiful conceptual progression: to have (habēre) becomes to have repeatedly (habitāre), which becomes to dwell — because dwelling is the sustained, repeated act of having a place.
The PIE root *gʰabʰ- (to give, to receive) underwent a remarkable semantic shift in Latin, where 'receiving' became 'having.' This same root produced Germanic 'geben' (German, to give) and 'give' (English) — showing that the original PIE word was ambivalent between giving and receiving, two sides of the same transaction. In Latin, the 'receiving' side prevailed and became 'having.'
The word family from Latin 'habēre' and 'habitāre' is enormous. 'Habit' entered English from Latin 'habitus' (condition, appearance, dress), the past participle of 'habēre.' A habit is something one 'has' — a condition, a disposition, a customary practice. The religious 'habit' (a monk's or nun's garment) is what one 'has on,' one's customary dress. 'Habitual' extends this: done as a habit, customary.
Latin Roots
'Habitat' is the place where an organism customarily dwells — its usual 'having-place.' The word entered English as a technical term from New Latin in the eighteenth century, when Linnaeus used 'Habitat in...' (it dwells in...) in his taxonomic descriptions. English adopted the Latin verb form as a noun.
'Inhabit' (to live in), 'cohabit' (to live together), 'exhibit' (to hold out, to display — from 'ex-' out + 'habēre'), 'prohibit' (to hold before, to prevent — from 'pro-' before + 'habēre'), and 'inhibit' (to hold in, to restrain — from 'in-' in + 'habēre') all belong to this family. Even 'able' may be distantly connected through Old French 'habile' (capable), from Latin 'habilis' (easily managed, apt), from 'habēre.'
The distinction between 'inhabitant,' 'resident,' 'citizen,' and 'denizen' is one of emphasis. An 'inhabitant' simply lives in a place — the word implies physical presence without legal status. A 'resident' also lives in a place but often implies a degree of permanence or official recognition. A 'citizen' has legal membership in a political community. A 'denizen' (from Old French 'deinzein,' one within) implies belonging to a place, naturalization, or simply being a regular presence. Each word slices the concept of 'living somewhere' at a different angle.
Later History
In legal and constitutional language, 'inhabitant' has specific weight. The U.S. Constitution uses 'inhabitant' rather than 'citizen' in certain clauses — for instance, requiring that members of Congress be inhabitants of the states they represent. The choice of 'inhabitant' over 'citizen' was deliberate: it required physical presence and residence, not merely legal membership.
The word 'inhabitant' thus carries within it a philosophy of place: to inhabit is not merely to occupy space but to have it habitually, to make it one's own through the sustained practice of dwelling. The etymology connects living to having, having to habit, and habit to the fundamental human act of making a place into a home.