Vigor
Adverb and Noun
いきおい
私達の犬は、誰と競争している訳でもないのに、いつもすごい勢いでミルクボーンに向かって行きます。
Our dog always bolts towards the milk-bone even though he isn’t racing anyone.
This is a single kanji with an い on the end, which means you think it ought to be an adjective, but it's not, it's a noun :( What's the noun form of force? It's also force.
This is a rough one. There is much force behind you, so when you come at me I scream: "EEK! OI! (いきおい), Get away from me!"