को as differential object marker

Hindi does not mark every direct object alike. को ko strongly favors objects that are high in animacy and identifiable in the conversation: people, particular animals, and entities construed as specific or strongly affected. This is differential object marking (DOM)—the marker signals how the speaker presents the object, not simply the verb's English translation.

The most useful scale is not “people take को, things do not.” Human and specific objects strongly favor it; nonspecific and inanimate objects often remain unmarked; the middle permits choices that change the construal. In perfective transitive clauses, the choice also affects agreement with marked objects.

Specific human objects strongly favor को

A known, particular human direct object is normally को-marked. Names do not change form, but changing nouns become oblique before को.

The demonstrative उस, the numeral phrase दोनों, and the discourse setting all make these referents identifiable. Omitting को from such singular specific human objects is not neutral standard Hindi.

Pronoun objects use conventional forms: मुझे, हमें, तुम्हें, आपको, इसे/उसे, इन्हें/उन्हें. Personal pronouns are inherently highly definite, so an ordinary direct-object reading cannot use bare मैं, वह, or वे.

Unmarked objects and low individuation

Inanimate objects, substances, and nonspecific kinds commonly remain unmarked. The unmarked object is not necessarily indefinite: a demonstrative can identify an inanimate object without forcing को.

Here वह किताब is definite, yet it is naturally unmarked. This shows why definiteness is only one conditioning factor. Inanimacy and an ordinary accomplishment reading support no को; चाय is a substance-like object with low individuation.

Human plurals can also be unmarked when the intended meaning is nonspecific, generic, or role-based rather than a known group.

No particular engineers have been identified. If the company is looking for a known group, कंपनी उन इंजीनियरों को ढूँढ़ रही है makes that group specific and को becomes natural.

A meaningful choice with inanimate objects

For some inanimate objects, both an unmarked phrase and a को-marked phrase are grammatical. को presents the referent as more individuated, contrastive, or boundedly affected.

The first sentence simply reports viewing a definite film. The second singles the film out as the deliberate target of repeated, exhaustive attention. को does not mechanically mean “the,” but it can support this strongly individuated construal.

A similar contrast appears with a bounded set:

The second sentence directs attention to a previously identifiable set. A speaker could still omit को with a demonstrative in many contexts; adding it increases individuation and often contrast. This is a genuine choice, not free variation with no meaning.

Verb meaning and affectedness

Some predicates strongly favor an animate marked object because their semantics normally target a particular individual: बुलाना “call/summon,” मारना “hit/kill,” पहचानना “recognize,” and बचाना “save.” With verbs such as पढ़ना “read,” खाना “eat,” or ख़रीदना “buy,” inanimate objects are commonly unmarked unless the speaker deliberately individuates them.

Affectedness matters because a wholly targeted or delimited participant is easier to construe as individuated. Nevertheless, को is not an “affected object” suffix: lexical convention and discourse status still matter. Learn frequent verbs in natural clauses rather than assigning one absolute rule.

Object marking is not recipient marking

The same surface को has more than one grammatical function. With देना “give,” a human phrase is usually the recipient, while the thing transferred is the direct object.

रीना को is the recipient; unmarked नई चाबी is the transferred object. By contrast, in मैंने रीना को देखा, Reena is the direct object and को is DOM. The verb's argument structure determines the role. DOM has no literal spatial meaning; it is a grammaticalized marker of the object’s discourse and semantic status.

को changes perfective agreement

In a perfective transitive clause with ने, an unmarked direct object can control verb gender and number. A को-marked object cannot. If both agent and object are postpositionally marked, standard Hindi uses default masculine singular agreement.

The agreement contrast is audible and meaningful: unmarked feminine plural चिट्ठियाँ licenses पढ़ीं; को blocks that agreement, producing default पढ़ा. Outside this perfective ergative configuration, ordinary subject agreement applies: सीमा उन चिट्ठियों को पढ़ रही है, with feminine रही agreeing with Seema.

A natural exchange

The specific human object डॉक्टर takes को. The inanimate unmarked रिपोर्ट controls feminine दिखाई in the perfective clause.

Common Mistakes

1. Treating definite inanimates as obligatorily marked

With deliberate contrast, मैंने उस किताब को ख़रीदा is grammatical: को gives the book a strongly individuated construal, and ख़रीदा is default masculine singular. The mistake is treating that marked pattern as automatic for every definite object.

2. Omitting को from a specific human object

3. Keeping a changing noun direct

4. Agreeing with a को-marked object

Key Takeaways

• Specific human objects strongly favor को; ordinary inanimate and nonspecific objects often remain unmarked.
• Definiteness alone does not force को: वह किताब can be a definite unmarked object.
• In the middle of the scale, को increases individuation, contrast, or bounded affectedness.
• In a ने perfective clause, an unmarked object may control agreement; a को-marked object cannot.