For the sister of your spouse:
* cunhada (pronounced "koon-YAH-duh") - This is the most common and general term for sister-in-law.
For the wife of your sibling:
* cunhada (pronounced "koon-YAH-duh") - This term is also used for the wife of your brother or sister.
Note: There isn't a separate word in Portuguese to distinguish between the sister of your spouse and the wife of your sibling. Both are referred to as "cunhada".