con-spondĕo

I. to engage or promise something mutually (ante- and postclass. and very rare): NEVE. CONSPONDISE. NEVE. CONPROMESISE. VELET., S. C. Bacch.; Wordsworth, Fragm. and Spec. p. 172: consponsi, Naev. ap. Varr. L. L. 6, § 70 Müll.; cf. Paul. l. l.: consponsa factio, App. M. 5, p. 168, 8; so, foedus, Aus. Ep. 10, 11.