申し込む

1. Origins, structure, and basic meaning

• Structure: 申し込む, read もうしこむ, means formally applying or signing up to participate in or use something.
• Basic usage: In 市民講座に参加するため、ウェブサイトから申し込んだ。, the speaker applied online to take part in a public course.

2. Common pitfalls and similar expressions

• Past form of a verb ending in む
  • The past form of 申し込む is 申し込んだ: the final む changes to んだ.