Sanskrit
इदं शरीरं कौन्तेय क्षेत्रमित्यभिधीयते । एतद्यो वेत्ति तं प्राहुः क्षेत्रज्ञ इति तद्विदः ॥
idaṃ śarīraṃ kaunteya kṣetram ity abhidhīyate etad yo vetti taṃ prāhuḥ kṣetrajña iti tadvidaḥ
Translation
This body, son of Kuntî, is called the Field; that which knoweth it is called the Knower of the Field by the Sages.
Annie Besant · The Bhagavad-Gita, translated by Annie Besant (4th ed., 1922) — Wikisource · Public Domain
Explanation
Krishna answers with maximum economy: “this body… is called the Field; that which knows it is called the Knower of the Field.” Kshetra — literally a plot of land under cultivation — becomes the chapter’s term for the entire arena of embodied experience: body, mind, and the objects it engages. Kshetrajna is simply the awareness that observes that arena without being identical to it. Notice the definition is structural, not descriptive — it says how to locate the knower (whatever is aware of the field), not what it’s made of, which is what verse 23’s fuller list of names is for.