Informal the essential facts or principles of a (specified) subject or activity: used in comb. and postpositively: a person who is ignorant of Flirting 101
Origin of 101in allusion to a numeric affix commonly used in naming high-school and college introductory courses
From the practice in US colleges of numbering courses, the initial course normally ending in 101
- A thoroughly large number. Used especially in book titles.
Symbolizing more than 100, an already large number.