Noun
Usually written in kana
1. thing; matter
そんなことは一言も言っていないでしょう。I never said a single word of the sort.
2. incident; occurrence; event; something serious; trouble; crisis
何かことが起きたら、すぐに連絡してください。If anything happens, please contact me right away.
3. circumstances; situation; state of affairs
4. work; business; affair
5. after an inflectable word, creates a noun phrase indicating something the speaker does not feel close to
Suffix
Usually written in kana
6. nominalizing suffix
この場で結論を出すことはどの国も難しいと思う。I think it is difficult for any country to reach a conclusion on the spot.
7. pretending to ...; playing make-believe ...
Noun
Usually written in kana
8. alias; also known as; otherwise known as; or
as AことB (A = alias, B = real name)
9. necessity; need
as 〜ことはない
そこまで気を使うことないよ。You don't need to worry that much.
10. you should ...; I advise that you ...; it's important to ...
as 〜ことだ