Origins
Option is a word about the power to choose, and its history reflects that power. It comes from Latin optiō, meaning 'free choice', from the verb optāre — 'to choose, to wish, to desire'.
The Roman military preserved the word in its purest form. An optiō was a centurion's second-in-command, and what made the rank distinctive was how it was filled: the centurion chose his own deputy. Where other ranks were assigned by superiors, the optiō was a personal selection — an option exercised by the person it mattered to most.
The Latin verb optāre may trace to Proto-Indo-European *h₃ep-, meaning 'to work' or 'to have abundance'. If so, the etymology suggests that choice requires surplus — you can only choose when you have more than one possibility. Scarcity eliminates options.
Development
The word entered English late, in the 17th century, borrowed from French. English already had choice (from French choisir) and pick (from Germanic), but option carried a formal, legal weight that the others lacked. An option is not just a choice — it is a right to choose, with defined terms and expiry.
Financial options — the right to buy or sell at a set price — formalised this meaning in the 18th century. A stock option is literally a purchased right to choose. The holder can exercise the option or let it expire. The choice itself has monetary value.
Optimism belongs to the same family. Latin optimus meant 'best', and an optimist is one who chooses to expect the best outcome.