徹底【てってい】
thoroughness, completeness, consistency, thorough enforcement, seeing to it that a policy, etc. is carried out without exception
海底【かいてい】
bottom of the ocean, seafloor, seabed, undersea, submarine
根底【こんてい】
root, basis, foundation
底力【そこぢから】
hidden reserves of strength, latent energy, potentiality, real strength
底値【そこね】
bottom price
到底【とうてい】
(cannot) possibly, (not) by any means, (not) at all, utterly, absolutely
川底【かわぞこ】
riverbed
谷底【たにぞこ】
valley floor, bottom of a gorge, bottom of a ravine