2、词根arthr, 关节，来自词根ar, 连接。-itis, 炎症。
2、arthritis:  Greek árthron meant ‘joint’ (it is used in various technical terms in biology, such as arthropod ‘creature, such as an insect, with jointed limbs’). It came from the Indo-European root *ar- ‘put things together, join, fit’, which also produced Latin artus ‘limb’ (source of English article) and English arm, as well as art. The compound arthritis is a Greek formation (-itis was originally simply an adjectival suffix, so arthritis meant ‘of the joints’ – with ‘disease’ understood; its application to ‘inflammatory diseases’ is a relatively modern development); it reached English via Latin.=> arm, art, article
4、"inflammation of a joint,"1540s, from medical Latin arthritis, from Greek (nosos) arthritis"(disease) of the joints,"from arthritis, fem. of arthrites (adj.)"pertaining to joints"(Greek nosos is a fem. noun), from arthron"a joint"(see arm (n.1)).