Vocabulary consisting only from characters you are able to read
防水
bousui
waterproofing, making watertightsuru
円の表面積は2πrである。
en no hyoumenseki ha 2paia-ru dearu.
Surface area of a circle is 2πr.math
陰口
kageguchi
malicious gossip, backbiting, speaking ill behind someone's backkaiwa