to run together, to associate DN.i.248; DN.ii.223; SN.ii.158 = Iti.70; SN.iv.379; Pp.32
caus saṃsandeti to put together; unite, combine Ja.i.403; Ja.v.216; Mil.131; Dhp-a.ii.12; Dhp-a.iv.51.

saṃ + syand, cp. BSk. saṃsyandati Avs.ii.142 sq., Avs.ii.188