Is Tejasvī, a masculine or feminine term or name in Sanskrit?
We see Tejasvī (with a long I) being used as a name for Indra in the Mahābhārata:
01,189.028 vyāsa uvāca
01,189.028a etac chrutvā vajrapāṇir vacas tu; devaśreṣṭhaṃ punar evedam āha
01,189.028c vīryeṇāhaṃ puruṣaṃ kāryahetor; dadyām eṣāṃ pañcamaṃ matprasūtam
01,189.028d*1916_01 viśvabhug ṛtadhāmā ca śibir indraḥ pratāpavān
01,189.028d*1916_02 śāntiś caturthas teṣāṃ vai tejasvī pañcamaḥ smṛtaḥ
Vyasa continued, 'Hearing these words of the former Indras, the wielder of the thunderbolt once more addressed that foremost of gods, saying, 'Instead of going myself, I shall, with a portion of my energy, create from myself a person for the accomplishment of the task (thou assignest) to form the fifth among these!' Vishwabhuk, Bhutadhaman, Sivi of great energy, Santi the fourth, and Tejaswin, these it is said were the five Indras of old.
Tejasvī is also used as an adjective for a female child:
कन्यामरगर्भाभां ज्वलन्तीमिव च श्रिया । तां ददर्श समुत्सृष्टां नदीतीरे महानृषिः ॥८॥
स्यूलकेशः स तेजस्वी विजने बन्धुवर्जिताम् । स तां दृष्ट्रा तदा कन्यां स्थूलकेशो महाद्विजः ॥९॥
01,008.007c kanyām amaragarbhābhāṃ jvalantīm iva ca śriyā
01,008.008a tāṃ dadarśa samutsṛṣṭāṃ nadītīre mahān ṛṣiḥ
01,008.008c sthūlakeśaḥ sa tejasvī vijane bandhuvarjitām
01,008.009a sa tāṃ dṛṣṭvā tadā kanyāṃ sthūlakeśo dvijottamaḥ
The great Rishi saw the girl lying forsaken in a lonely place on the banks of the river, blazing in beauty; she was as beautiful as a child of an immortal. And the great Brahmana,
Sthulakesha, the chief of Munis, finding that female child.