偶然

1. Origins, structure, and basic meaning

• Structure: 偶然 is read as ぐうぜん and functions as a noun or adverb for something happening by chance rather than by intention or expectation.
• Basic usage: Meeting someone by chance appears in 偶然会う, while judging something a mere coincidence appears in 単なる偶然だ.

2. Common pitfalls and similar expressions

• Noun and adverb uses
  • It behaves like a noun in 偶然だ and like an adverb describing how an action occurred in 偶然会う.
• Difference from たまたま
  • Both can mean by chance, but たまたま is common as a conversational adverb, while 偶然 also naturally forms noun predicates.