Concentrating

verb

1. To bring to, or direct toward, a common center; to unite more closely; to gather into one body, mass, or force.

   "to concentrate rays of light into a focus"

2. To increase the strength and diminish the bulk of, as of a liquid or an ore; to intensify, by getting rid of useless material; to condense.

   "to concentrate acid by evaporation"

3. To approach or meet in a common center; to consolidate.

   "Population tends to concentrate in cities."

4. To focus one's thought or attention (on).

   "Let me concentrate!"