From Longman Dictionary of Contemporary Englisha great/good deala great/good dealLOT/LARGE NUMBER OR AMOUNTa large quantity of something SYN a lota great/good deal of It took a great deal of time and effort. His work has been attracting a great deal of attention.a great/good deal more/less etc (=a lot more, less etc) He knew a good deal more than I did. She’s married to a man a good deal older than herself.GRAMMAR: Comparisona great/good deal of• You use a great deal of or a good deal of with uncountable nouns: a great deal of moneya good deal of work• A great/good deal of is not used with nouns in the plural. ✗Don’t say: a great deal of peoplea lot of• You can use a lot of with nouns in the plural or uncountable nouns: a lot of peoplea lot of trouble → deal
Examples from the Corpus
a great/good deal• The movement of earthworms throughout layers can also cause a great deal of disruption, blurring the divisions.• Very frequently, speechwriters are recruited from the ranks of journalism, which accounts for a great deal.• In the last ten years, we have learned a great deal more about this interplay.• Teachers also received a great deal of support and help from both popular organizations and from communities to ease their situation.• She spoke a great deal about poetry.• A single incident suggests a great deal about Hennepinhis prudery, his belligerence, his sensitivity.• One particular candidate responding to the survey went to a great deal of trouble to commit his decidedly anti-headhunting views to paper.• Neither girl took a great deal of interest in me. 