The Collaborative International Dictionary of English v.0.48:

Rheumatic \Rheu*mat"ic\, n.
   One affected with rheumatism.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Rheumatic \Rheu*mat"ic\, a. [Gr. ??? subject to a discharge or
   flux: cf. L. rheumaticus, F. rhumatique. See Rheum,
   Rheumatism.]
   1. Derived from, or having the character of, rheum; rheumic.
      [Obs.]
      [1913 Webster]

   2. (Med.) Of or pertaining to rheumatism; as, rheumatic pains
      or affections; affected with rheumatism; as, a rheumatic
      old man; causing rheumatism; as, a rheumatic day.
      [1913 Webster]

            That rheumatic diseases do abound.    --Shak.
      [1913 Webster]

WordNet (r) 3.0 (2006):

rheumatic
    adj 1: of or pertaining to arthritis; "my creaky old joints";
           "rheumy with age and grief" [syn: arthritic, creaky,
           rheumatic, rheumatoid, rheumy]
    n 1: a person suffering with rheumatism

Moby Thesaurus II by Grady Ward, 1.0:

53 Moby Thesaurus words for "rheumatic":
   allergic, anemic, apoplectic, arthritic, bilious, cancerous, case,
   chlorotic, colicky, consumptive, dropsical, dyspeptic, edematous,
   encephalitic, epileptic, incurable, inpatient, invalid, laryngitic,
   leprous, luetic, malarial, malignant, measly, nephritic, neuralgic,
   neuritic, outpatient, palsied, paralytic, patient, phthisic,
   pleuritic, pneumonic, pocky, podagric, rachitic, rickety,
   scorbutic, scrofulous, shut-in, sick person, spastic, sufferer,
   tabetic, tabid, terminal case, the sick, tubercular, tuberculous,
   tumorigenic, tumorous, valetudinarian