OBJECTIVES: To describe how pain descriptors are used to represent patients’ pain experiences by mapping word clusters identified by patients as synonyms for the same pain sensation. METHODS: Subjects were recruited by web posting and telephone screening.  Those self-reporting current pharmacological treatment for Migraine, Low Back Pain (LBP), Osteoarthritis (OA), or Rheumatoid Arthritis (RA) were enrolled and completed in-person interviews using card sort exercises with 93 different pain descriptors. Subjects were asked to identify the descriptors they commonly used to describe the pain associated with their condition, and to isolate any pairs of words that describe the same pain sensation (‘linked’ descriptors). Network maps that diagrammed subject-identified links between descriptors were created for each condition using Netdraw (Borgatti 2002) and compared. RESULTS: The 72 subjects ranged in age between 19 and 84 years (mean=45).  Sixty-eight percent were female, 63% were working full- or part-time, and 61% were Caucasian. OA and Migraine subjects used more synonyms to describe similar pain experiences (14% and 10% of all identified synonym pairs, respectively) than the LBP and RA groups (at 7% and 6%). For Migraine, most linked descriptors formed a single group of connections, or single integrated relationship. For the OA group, several smaller unassociated subgroups of synonyms were identified. For the LBP group, two main clusters emerged, differentiating low-intensity and high-intensity pain. For the RA group, several descriptors were weakly linked to only one other descriptor. Some synonyms were common to all four groups (e.g., STIFFNESS-TIGHTNESS), but others were condition-specific (e.g., SPREADING-RADIATING for OA, but SPREADING-GNAWING for Migraine). CONCLUSIONS: While some descriptors were used to convey a more consistent meaning across groups, other descriptors’ synonyms varied by condition, demonstrating condition-specific meaning. These findings emphasize the importance of tailoring item language to the specific population of interest when assessing pain with PRO instruments.