adjective /tænˈdʒɛn.tʃəl,tænˈdʒɛnt.ʃəl,tænˈdʒɛn.ʃəl/
a) Referring to a tangent, moving at a tangent to something.
The meteor came in on a tangential orbit and exploded about 8 or 10 miles above the earths surface, just south of the Arctic Circle
b) Merely touching, positioned as a tangent.
The archoplasm divides and forms a very large spindle which first lies tangential to the surface of the nucleus.
Wikipedia foundation.