V. S. Apte, The Practical Sanskrit–English Dictionary. Look up any word of the Gita in Devanagari, IAST or Harvard-Kyoto, or browse the headwords letter by letter.
vettāsi vedyaṁ ca paraṁ ca dhāma — Thou art the ancient Soul and the first and original Godhead and the supreme resting-place of this All; Thou art the knower and that which is to be… 11·38
वेत्तvettanominative singular of the masculine noun vettṛ (the knower).