Yes It is Correct! Source- http://en.wikipedia.org/wiki/Onomatopoeia
You just spelled it correctly, excellent job.
Yes it is spelled correctly
No, onomatopoeia refers to words that are spelled the way they sound as in bang, kaboom, crash.
You have spelled 'still' correctly.
onomatopoeia
Yes, engineer is spelled correctly in your question.
Flattest is spelled correctly. The others are spelled: silliest, biggest and sweetest.
Yes, surprisingly is spelled with an S. Surprisingly is how you spell it. You spelled it correctly.
You've spelled it correctly.
Convenience (easy access or availability) is correctly spelled.
yes, that is correct.
It should be foreign.