term:

Swear

swear vb

swore
sworn
swear·ing
[Old English swerian]
vt
1 : to utter or take solemnly [ an oath]
2 a : to assert as true or promise under oath [a sworn affidavit]
b : to assert or promise emphatically or earnestly [swore to uphold the constitution]
3 a : to put to an oath
b : to bind by an oath
vi
: to take an oath

Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.