Significant or important; major: a bigtime comedian. (adjective)
To an extreme degree; very much: Sales are expanding, big-time. (adverb)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "bigtime" in a sentence
"He knew he would lose the state bigtime which is why he pulled out."
"Many women from the Indy ranks have made it into the "bigtime", the WWE and TNA."
"The earliest "bigtime" band I can remember seeing would have to be ... hmmm ...."