For general topics or subjects:
* Concerning: "He was concerned about the meeting."
* Regarding: "She had a lot to say regarding the new policy."
* On: "We talked on the latest news."
* Regarding: "I have some thoughts regarding the upcoming project."
* In regards to: "In regards to your question, I can't give you a specific answer."
* On the subject of: "On the subject of your proposal, I have some concerns."
* Relating to: "There are several issues relating to the budget."
For approximate quantities or numbers:
* Around: "There were about 100 people at the party."
* Approximately: "The building is approximately 100 years old."
* Nearly: "It's nearly 10 o'clock."
* Roughly: "The journey took roughly two hours."
For actions or events:
* To: "He was about to leave."
* On the verge of: "She was on the verge of tears."
* Close to: "We're close to finishing the project."
For specific details or information:
* Concerning: "I have some information concerning the case."
* Regarding: "We need to discuss the details regarding the contract."
* In relation to: "I need to know more in relation to your plans."
* With respect to: "With respect to your request, I can't provide an answer yet."
For opinions or feelings:
* On: "I have strong opinions on the matter."
* Regarding: "I'm excited regarding our upcoming trip."
* Regarding: "He was anxious about the exam."
It's always best to consider the specific context and meaning you want to convey when choosing a synonym for "about."