B.G 10.31
pavanaḥ pavatām asmi rāmaḥ śastra-bhṛtām aham। jhaṣāṇāṁ makaraś ca asmi srotasām asmi jāhnavī ॥31॥
I am the wind among purifiers, Rāma among wielders of weapons; among aquatic creatures, I am the makara, and among rivers, I am the Gaṅgā (Jāhnavī).
Gīta Bhāshya 10.31
'Rāma' - one who is of the nature of bliss, complete, and delights the worlds.
ānanda-rūpatvāt pūrṇatvāt loka-ramaṇāt ca rāmaḥ
He is called Rāma because He is of the nature of bliss, complete, and delights the worlds.
"ānanda-rūpo niṣparīmāṇa eṣa lokaś ca etasmāt ramate tena rāmaḥ"
"He is of the nature of bliss, immeasurable; and the world delights in Him — therefore He is called Rāma."
-iti śāṇḍilya-śākhāyām
- stated thus in the Śāṇḍilya branch of Vedic testimonial.
raś ca amaś ca iti vyutpattiḥ ॥31॥
The etymological derivation is ‘ra’ + ‘ama’.