A common plain-language definition of "introvert" used by professionals is that introverts "are more often energized from their quiet time than their social time"[1]. Extroverts are the opposite. Note that introversion and extroversion are on a continuum with most people in the general population (maybe not a specific population) being towards the middle.

Three comments to address your question specifically:

1. Note the "more often" in the definition. It isn't "always". As such, sometimes introverts are energized by their social time.

2. Given the spectrum of extroversion and introversion, some folks may be less extreme and therefore exhibit less stereotypical behavior for their archetype.

3. Extreme introversion (or extroversion) is not perceived as being pathological until it "causes impairment in functioning and/or causes significant distress for the individual" [ibid]. This might be in the form of detachment that has some surface level similarities to being an extreme introvert, but is actually quite different.

[1] https://www.psychologytoday.com/blog/self-promotion-introver...