to pronounce in an important (because secret) manner (like a mantra), i.e.

1. to take counsel (with = instr. or saddhiṃ) DN.i.94, DN.i.104 (mantanaṃ manteyya to discuss DN.i.122 (2^nd pl. imper. mantavho, as compared with mantayavho Ja.ii.107 besides mantavho ibid. Cp Geiger, P.Gr. § 126); DN.ii.87, DN.ii.239; Vin.iv.308 (mantesuṃ aor.; perhaps “plotted”); Snp.p.107 (= talk privately to); Snp.379; Ja.i.144; Ja.vi.525 (mantayitvāna ger.) DN-a.i.263 (imper. mantayatha); Pv-a.74 (aor. mantayiṃsu).
2. to consider, to think over, to be of opinion AN.i.199 (Pot. mantaye); Mil.91 (grd. mantayitabba & inf.; mantayituṃ).
3. to announce, advise; pronounce advise Snp.126; Pv.iv.1#20 (= kathemi kittayāmi Pv-a.225); Snp-a.169

pp mantita
■ Cp. ā˚.

cp. Vedic mantrayati; mant is given at Dhtp in meaning of gutta-bhāsana, i.e. “secret talk”