The incorrectly spelled word is:

☀ Patrner

The correct spelling is "Partner." Partner refers to a person who shares or is associated with another in some activity or endeavor.

The other options are spelled correctly:

• Pierce: Means to make a hole or opening by penetrating or cutting through.
• Piteous: Describes something that evokes or expresses pity or compassion.
• Pursue: Means to follow or chase with the intent of reaching or capturing.