atomic nucleus / (algebra) kernel / (astronomy) core, nucleus / cell nucleus

refine / train / tempering / drill / polish

The katakana syllable ブ (bu). Its equivalent in hiragana is ぶ (bu).

clever, discerning, wise

clothes; wrap; put on

(archaic) iron / (figuratively) something extremely strong

(mahjong) hand of man: win by discard on the first go-around of play; depending on the rules, it can be worth 役満 (yakuman, “limit”), 倍満 (baiman), 満貫 (mangan), or any other number of points

(mahjong) the retainment of the east or 親 (oya, “dealer”) position after a win / (by extension) events that are repeated or in a series

iron

iron, the metal and the metallic chemical element / (more generally) steel / short for 鉄砲 (teppō, literally “cannon”, but in this case, refers to the poisonous fugu blowfish or dishes made from it)