English Reference
adjective · noun

proprietary

adj. · n.
US /pɹəˈpɹaɪəˌtɛɹi/ UK /pɹəpɹˈaɪətəɹi/ pro·pri·etary UK spelling proprietaries

  1. 01 C1 Advanced TechnicalAcademic Law

    adj.describing something that is owned by a company and cannot be used or copied by others without permission.

    adj.relating to an owner or ownership; specifically, manufactured and sold only by the owner of the intellectual property rights.

    Simple

    The company uses proprietary software that no other business is allowed to buy.

    In context

    The pharmaceutical giant maintains proprietary rights over the formula, preventing generic manufacturers from producing a cheaper version for the next decade.

    Usage

    Often used before nouns like 'software', 'technology', or 'information'.

    open sourcepublic
  2. 02 C2 Proficiency Literary

    adj.behaving as if you own something or someone, often in a way that shows you are protective or jealous.

    adj.expressing or manifesting a sense of ownership or exclusive rights, often used to describe a person's protective attitude or physical stance.

    Simple

    He put a proprietary arm around his daughter as the strangers approached.

    In context

    She watched the restoration of the old house with a proprietary interest, despite having sold the property several months earlier.

  3. 03 C2 Proficiency FormalArchaic Law

    n.a person who owns a business or a piece of land.

    n.an individual or entity that holds legal title to a property or business.

    Simple

    The proprietary of the estate decided to open the gardens to the public.

    In context

    The original charter granted the proprietary full authority over the colonial territory, including the right to collect taxes and appoint local officials.

    Teacher's tip

    In modern English, the noun 'proprietor' is much more common than using 'proprietary' as a noun.

Many remote sensing products rely on proprietary processing that researchers cannot fully access and verify, while some wildlife tracking devices provide only processed animal locations while withholding the underlying raw data.

Phys.org· 15 Aug 2026

AI companies often offer models in proprietary, open-weight and smaller open-source versions .

The Conversation· 12 Aug 2026

From French propriétaire, from Latin proprietārius. By surface analysis, propriety + -ary. Compare with the Latin proprietas (“property”) and proprius (“ownership”).

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin Latin proprietārius
Level C1 · Advanced
Frequency Frequent
Updated