To Struggle, To Fight
intransitive verb, godan verb
Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means struggle so the verb version is to struggle or to fight. This struggle is fairly figurative, too. It's more like "the struggle against terrorism" or "the fight against drugs." Not so much a fight with people, which would be 戦う.
たたかう
Your neighborhood is fighting a struggle against car theft. Sadly, your car was stolen. So, you say: "ta-ta, car (たたか). Ta-ta."
この子たちは、みんな病気と闘っているんです。
These kids are all fighting against their diseases.