1To call out to someone in order to get their attention or a response.
後ろから名前を呼びかけられて、驚いて振り返った。
Someone called my name from behind, and I turned around, surprised.
先生は教室に入ると、生徒たちに明るく呼びかけた。
When the teacher entered the classroom, she cheerfully called out to the students.
遠くにいる友人に大声で呼びかけたが、聞こえなかったようだ。
I called out loudly to my friend in the distance, but they didn't seem to hear me.
2To appeal to the public or a wider group, urging cooperation or action.
市は台風に備えて、住民に早めの避難を呼びかけた。
The city urged residents to evacuate early in preparation for the typhoon.
医師会は手洗いの徹底を国民に呼びかけている。
The medical association is urging the public to thoroughly wash their hands.
彼女はSNSで献血への協力を呼びかけた。
She used social media to appeal for cooperation with blood donation.