Nouns

(n)focus, focal pointa point of convergence of light (or other radiation) or a point from which it diverges
(n)focus, focal point, nidusa central point or locus of an infection in an organism“the focus of infection”
(n)focus, focusing, focussing, focal point, direction, centering, centringthe concentration of attention or energy on something“the focus of activity shifted to molecular biology”, “he had no direction in his life”