Lexical Definition

‎συνεπιμαρτυρέω‎ synepimartyréō (soon-ep-ee-mar-too-reh'-o) to testify with ^G:V
from ‎σύν‎ and ‎ἐπιμαρτυρέω‎

also bear witness.

• to testify further jointly, i.e. unite in adding evidence

Abbott-Smith

* συν-επι-μαρτυρέω, -ῶ
to join in attesting, bear witness together with: He 2:4 (Arist., Polyb., al.).†

Abbott-Smith References

Liddell-Scott-Jones

συνεπιμαρτυρέω-έω,

join in attesting, [NT+4th c.BC+]; τινι with one, [Refs 2nd c.BC+]; add one's evidence, [Refs 1st c.AD+]

__II Astrology texts, to be also configurate, of planets, [Refs 2nd c.BC+]

_{LSJ Scripture Refs: Heb.2.4}