* Section: This is probably the closest synonym, referring to a distinct part of a larger piece of writing.
* Passage: This implies a portion of text, but it's less precise than paragraph.
* Stanza (in poetry): A stanza is a paragraph in poetry, marked by line breaks and often a change in rhyme or rhythm.
* Piece: A general term referring to a segment or part of writing.
* Portion: Similar to "piece" or "passage."
The best substitute will depend heavily on the context. For example, "section" works well when discussing a formal document, while "passage" might be better for a more informal piece of writing.