From BiblePortal Wikipedia

Smith's Bible Dictionary [1]

Co'sam. (A Diviner). Son of Elmodam, in the line of Joseph, the husband of Mary.  Luke 3:28.

Hastings' Dictionary of the New Testament [2]

Cosam —A name occurring in the Lukan genealogy of our Lord ( Luke 3:28).

Hastings' Dictionary of the Bible [3]

COSAM . An ancestor of Jesus (  Luke 3:28 ).

Morrish Bible Dictionary [4]

Son of Elmodam in the genealogy of the Lord Jesus.  Luke 3:28 .

Fausset's Bible Dictionary [5]

 Luke 3:28. (See Genealogies .)

Holman Bible Dictionary [6]

 Luke 3:28

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [7]

( Κωσάμ , prob. for Heb. קֹסֵם , a Diviner ), son of Elmodam, and father of Addi, ancestors of Christ, and descendants of David in the private line, before Salathiel ( Luke 3:28), B.C. ante 588. He is not mentioned in the Old Testament. (See Genealogy (Of Christ).)

International Standard Bible Encyclopedia [8]

kō´sam ( Κωσάμ , Kōsám ): An ancestor of Jesus in Luke's genealogy in the 5th generation before Zerubbabel ( Luke 3:28 ).