What does the word 「なりそこなった」 mean?


Here is the sentence including the word.

> 自分がチャンピオンに **なりそこなった** もんだから このおれにゆめをたくそうってわけだな。




"[連用形] + 損【そこ】なう" is a common combination which means "fail to [verb]". See
definition #4 of [this
entry](http://dictionary.goo.ne.jp/leaf/jn2/130437/m0u/).

チャンピオンになりそこなう = to fail to become a champion

