Teja & Tejo

“sharpness,” heat, flame, fire, light; radiance, effulgence splendour, glory, energy, strength, power DN.ii.259 (personified as deva, among the 4 Elements paṭhavī, āpo, t., vāyo; cp. tejo-dhātu); SN.iv.215; MN.i.327; Snp.1097 (glory of the sun comp^d with that of the Buddha); Dhp.387 (sabbaṃ ahorattiṃ Buddho tapati tejasā); Ja.iii.53 (sīla˚); Ja.i.93 (puñña˚ the power of merit); Vb.426 (id.); Pts.i.103; Vism.350 (def.) Vv-a.116.

• -kasiṇa fire-contemplation for the purpose of kammaṭṭhāna practice (see kasiṇa) DN.iii.268; Dhs.203; Vism.171; Dhp-a.ii.49; Dhp-a.iii.214; Bdhd 106;
• -dhātu the element of flame (or fire), the 3rd of the 6 Elements, viz. paṭhavī āpo t. vāyo ākāsa viññāṇa (cp. Dhs. trsl. p. 242) DN.iii.27 DN.iii.228, DN.iii.247; MN.i.188, MN.i.422; AN.i.176; AN.ii.165; Dhs.588, Dhs.648 Dhs.964; Ne.74; Vism.363.

Vedic tejas (nt.) from tij to be sharp or to pierce = a (piercing) flame. See tejate; semantically (sharp → light) cp. Ger. strahl (ray of light) = Ags. strael (arrow)
■ The nt. tejo is the usual form; instr. tejasā (Dhp.387; Snp.1097) & tejena (Ja.iii.53), cp. tapa & tapo