The word 'tuberculous' is a medical adjective built directly upon the noun 'tubercle.' Its journey begins with the Latin tuber, meaning a lump or swelling, which itself may trace back to the Proto-Indo-European root teue-, meaning "to swell." The diminutive form tuberculum (a small swelling) was adopted into medical Latin to describe the characteristic lesions of the disease. By adding the adjectival suffix -ous (from Latin -osus), the term evolved to describe anything pertaining to or characterized by these tubercles, most specifically the infectious disease tuberculosis. Thus, the literal "full of small swellings" logically defines the pathological condition.

Structure: tubercul (small swelling) + ous (adjective suffix) - tubercul: From Latin tuberculum, a diminutive of tuber (lump, swelling). Its functional role is the core root conveying the concept of a small, rounded growth or nodule. - ous: A suffix of Latin origin (-osus) used to form adjectives meaning "full of," "having the qualities of," or "pertaining to."