one's heart, mind, true motives

boxing (the sport of boxing)

vacuum

heart failure

(Zen Buddhism) the teaching of intangible or abstract concepts in 仏法 (buppō, “dharma”) without using words / non-verbal communication, or the ability to immediately understand each other without words

(law) trial / (sports) referee, umpire / (tarot) Judgement

conviction, confidence in

epicenter(AmE), epicentre(BrE) - the point on the Earth's surface directly above the focus of an earthquake. / (figuratively) The focal point of any activity, especially if dangerous or destructive .

aggression / invasion / raid

close friend, bosom buddy / crony, chum