In some forms of karate and karate-derived systems... hmmm.... like TKD
, "uke" is often misconstrued to mean "block". E.g. shuto uke = knife hand "block" which is not the same as shuto uchi = knife hand strike. And if you're going to "block", you might as well be "blocking" or more appropriately, "striking" something nice and soft instead...
Uke literally means "receive"... and is a key concept in a number of JMAs as implying precisely that... to "receive" an attack, rather than to "block" it.
Tenkai, OTOH, is related to tai sabaki and is a tactical means of turning/pivoting the body around the central axis without moving the feet. It is part of the general strategy of body positioning and "blending" with an attack and is completely different to "blocking" or receiving.