WordNet sense 1 (special emphasis attached to something):

stress

WordNet sense 2 (a central point or locus of an infection in an organism):

nidus, focal point

WordNet sense 3 (the concentration of attention or energy on something):

direction, centering, focusing, focussing

WordNet sense 4 (bring into focus or alignment; to converge or cause to converge; of ideas or emotions):

concenter, concentre, focalise, focalize

WordNet sense 5 (direct one's attention on something):

center, concentrate, pore, rivet, centre

WordNet sense 6 (put (an image) into focus):

sharpen