tes·ti·fy /'tes-tə-ˌfī/ vb -fied, -fy·ing [Latin testificari, from testis witness]
vi: to make a solemn declaration under oath or affirmation for the purpose of establishing a fact: give testimony
vt: to declare in testimony
tes·ti·fi·er n
Merriam-Webster’s Dictionary of Law. Merriam-Webster. 1996.