- to do less or in a lesser fashion than is usual or requisite.
Origin of underdo
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for under-doing
"Over-doing in work is not likely to lead to under-doing a breakdown," Miss Bradbury replied to Mrs. Scollard's remark.Six Girls and Bob
Marion Ames Taggart