Lexical Definition

‎συνθάπτω‎ syntháptō (soon-thap'-to) be buried with ^G:V
from ‎σύν‎ and ‎θάπτω‎

bury with.

• to inter in company with, i.e. (figuratively) to assimilate spiritually (to Christ by a sepulture as to sin)

Abbott-Smith

* συν-θάπτω
to bury together with: in symbolical sense, of baptism, αὐτῷ (with Christ), Ro 6:4, Col 2:12.†

Abbott-Smith References

Liddell-Scott-Jones

συνθάπτω,

bury together, join in burying, τινα [Refs 5th c.BC+]; τινά τινι one with another, [Refs 5th c.BC+]:—passive, to be buried with, τῷ ἀνδρί [NT+5th c.BC+]

_{LSJ Scripture Refs: Rom.6.4}