In a conversational or informal manner; using everyday language rather than formal or technical speech.
From colloquial (from Latin colloquium meaning 'conversation between people') + -ly (adverb suffix). The word emerged in English by the 18th century as scholars and grammarians needed to describe informal speech patterns.
Colloquially is the word linguists use when they want to tell you 'normal people say it this way'—it's the escape hatch from stuffy language. Notice how every scientific paper uses it to admit that yes, technically a quasar is a 'quasi-stellar object,' but colloquially we just call it that one term.
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