To Accompany
intransitive verb, godan verb
Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means accompany and the verb vocab version is to accompany. This can be used both literally and figuratively.
You need to accompany your friend, so to call out to them you yell "友, NOW!" (ともなう) to command them to come near you to accompany you to somewhere else.
技術の進歩に伴って人々は自然環境にだんだん関心がなくなってきた。
As technology advanced, people grew less and less concerned about the environment.