'single-discipline-focused' is a Modern English compound formed from the adjective 'single' + the noun 'discipline' + the adjective-forming/past-participle element 'focused' (from 'focus').

'discipline' originates from Latin 'disciplina' via Old French 'discipline', where 'disciplina' comes from 'discipulus' meaning 'learner' (related to teaching and training). 'focus' comes from Latin 'focus' originally meaning 'hearth' and later used figuratively for a point of attention; 'focused' is the past participle/adjectival form of 'focus'. 'single' comes from Old English and Proto-Germanic roots meaning 'one' or 'alone'. These elements combined in Modern English to form the descriptive compound.

Initially, 'discipline' primarily referred to teaching or training (and later to a branch of learning), while 'focus' originally meant 'hearth' before shifting to 'point of emphasis'; combined in this compound, they now mean 'having emphasis restricted to one field'.