If "tract" refers to a piece of land:
* Parcel: A small piece of land, often used for building.
* Plot: A small area of land, often used for farming.
* Estate: A large area of land, often with buildings.
If "tract" refers to a written work:
* Dialogue: Conversation or discussion, as opposed to a written piece.
* Performance: A live presentation, as opposed to a written work.
* Experience: Personal knowledge or observation, as opposed to a written account.
If "tract" refers to a system of organs:
* Organism: A complete living being, as opposed to a specific organ system.
* System: A group of organs working together, but not necessarily the same specific system as the tract.
If "tract" refers to a direction:
* Opposite: The directly opposite direction.
* Divergent: Moving away from each other.
* Convergent: Moving towards each other.
Therefore, the best antonym for "tract" will depend on the specific context and the intended meaning.