Wiktionary
n. (context of marching bands English) an internal competition used to practice marching commands, in which the last person caught improperly executing a command wins vb. (context idiomatic English) to examine information at another level or in greater detail; especially in a database, to navigate to a more detailed level or record
Wikipedia
In information technology to drill down means to move from one place to another, information to detailed data by focusing in on something. In a GUI-environment, "drilling-down" may involve clicking on some representation in order to reveal more detail.
To drill down through a series of notebooks, for example, on a desktop means to move through the hierarchy of folders (from the top downwards) to find a specific file or to click through drop-down menus in a GUI. Clicking on an item moves you to a level of greater detail. When an online user accesses more and more pages of the website, he or she may delve deeper into the content of the site. As a web-surfer goes further into a website, he or she goes deeper into the back pages and thus deeper into data. (Of course, he or she could also begin—for example via an external search engine—at a detailed view, and drill up to the front page of the site.)
Drilling down through a database involves accessing information by starting with a general category and moving through the hierarchy: from category to file/table to record to field. When one drills down, one performs de facto data analysis on a parent attribute. Drilling down provides a method of exploring multidimensional data by moving from one level of detail to the next. Drill-down levels depend on the data granularity.
The field of managerial economics uses the term "Drill Down" to explain certain technical aspects of operations research and regression analysis.
For an alternative data-extraction metaphor, see data mining.
Usage examples of "drill down".
They built the drill shack, and in the early hours of April 27, sent the drill down into the frigid depths of Lac de Gras.
McFarlane watched as she expertly broke the drill down and examined its components.
Twenty minutes will suffice, counting the time required to drill down to it.
The only way to be sure you're sitting on an oilfield is to drill down and find out.
If I could only drill down to the roots of my behavior, in my past, I'd understand what I'm doing, and I'd be better.
I turned the hammer over to him, and he gave it a boost with his knee, brought the drill down on a patch of rock and cut in the air.
Sal snapped as she struck the repair tools and pieces of drill down in a canvas bag.