Definition

1. Verb (intransitive):
   • To attend or be present at a meeting, class, or event as a visitor or observer, not as a regular participant. This is the most common usage, implying passive attendance with permission.
   • To participate in a form of protest or demonstration by occupying a place, such as a building or office, and refusing to leave. This usage refers to an act of civil disobedience.

Examples of Usage

• Verb (as an observer):

  • The professor allowed me to sit in on the lecture to see if I liked the course.
  • May I sit in during your team meeting this afternoon?

• Verb (as a protest):

  • Students plan to sit in at the administration building until their demands are heard.
  • The activists sat in at the factory gates to protest the layoffs.

Advanced Usage

• "to sit in on something": This phrasal verb construction is almost always used when referring to attending as an observer. The preposition "on" is followed by the event (e.g., a meeting, a class, a session).

  • She asked to sit in on the board's deliberations.

• "to sit in for someone": This is a related but distinct phrasal verb meaning to temporarily take someone's place or perform their duties.

  • I will be sitting in for the manager while she is on vacation. (Note: This is listed as a related variant, not the core definition of "sit in").

Variants and Related Words

• Sit-in (noun): A form of protest in which demonstrators occupy a place. This is the noun form derived from the verb's protest meaning.

  • The sit-in lasted for three days before an agreement was reached.

• Sit in for (phrasal verb): To act as a substitute or temporary replacement.

  • Can you sit in for me at the committee meeting tomorrow?

Synonyms

• Observe: To watch or notice, especially in a formal context (for the observer meaning).
• Audit: To attend a class without receiving academic credit (specific to educational settings).
• Occupy: To take control or possession of a space, especially as a protest (for the protest meaning).

Related Phrasal Verbs

• Sit in on: To attend as an observer or visitor. This is the core phrasal verb for the primary definition.
  • Journalists were allowed to sit in on the closed-door hearing.

Related Idioms

• No direct idioms are primarily formed with "sit in." Its meanings are largely conveyed through the standard phrasal verb constructions "sit in on" and "sit in for."

Verb

1. participate in an act of civil disobedience
2. attend as a visitor
   • Can I sit in on your Intermediate Hittite class?