Never ever do things this like this in secret. It will come out sooner or later and will be looked upon badly, to the point where you may be fired.
As Alexander commented under your question:
It is the responsibility of the person managing the meeting to make sure you understood everything that was discussed. It should also be their responsibility to produce a documentation of all important points of the discussion
Go to your manager or to the person managing the meeting and discuss the issue with him. Not as a complaint, but ask him for guidance, so that you can work this out together.
In that conversation you could even bring up the suggestion of recording. If you decide to do so, the recording device should be clearly visible and switched on/off to all participants, you would have to make clear to everyone what the purpose of the recording is, and you should also destroy it a.s.a.p.*
In addition, one thing surprises me: if you are supposed to take notes (either for yourself or for others), why don't you just say things like:
- Sorry, can you repeat that. Did you mean X?
- So, to make it clear for me, did you mean we have to Y?
That would be taking responsibility instead of complaining afterwards.
Also, from experience, what really helps: go over your notes again (or work them out better) directly after the meeting (first thing). At that moment things are still fresh in your head, and you may even be able to contact a meeting attendee for clarification (it is still fresh in their head as well).
* You have to take away the fear that the recording can be used to hold people to their words three weeks later - nobody likes that.