All 16 words, sorted alphabetically. Group them into four categories of four.
The four category names, easiest to hardest. No words revealed yet.
Theme name plus one word from each category.
The abbreviation 'ID' can refer to Freud's concept of the id, the state of Idaho, a driver's license (ID card), or the act of identifying/recognizing someone.
The abbreviation 'IN' can refer to an inch (measurement), Indiana (state abbreviation), being inside, or being trendy/in fashion.
The abbreviation 'LA' can refer to lanthanum (element symbol), Los Angeles (city), Louisiana (state abbreviation), or the musical solfège note 'la'.
The abbreviation 'OK' can refer to the British celebrity magazine OK!, Oklahoma (state abbreviation), giving a greenlight/approval, or describing something as mediocre.