Scientific Wild-Ass Guess (SWAG) is a slang acronym used to describe a rough estimate basis an expert's experience or knowledge of the business. It is synonymous to guesstimate. Since it is an estimate, it does not involve exhaustive research or data analysis to arrive at the decision.
An application-oriented question on the topic along with responses can be seen below. The best answer was provided by Prashanth Datta on 22nd January 2019.
Applause for all the respondents- Prashanth, Shailendra, Himanshu, Vastupal
Also review the answer provided by Mr Venugopal R, Benchmark Six Sigma's in-house expert.