A converging at a common center
Concentration of the mental powers on something
The act of bringing together
Anything brought together
Jackson lost concentration in remembering her.
The place of concentration was Arisbe on the Hellespont.
The concentration at Rialto marks the beginning of the history of Venice as a full-grown state.
She mumbled something he could not understand until he forced concentration, eventually discerning the thin voice whispering The Lord's Prayer.
Her concentration was on the clothes, and he tried not to smile as she spent a minute petting a sweater.