thorns (thorny plants) / hardships, difficulties

the surface of the board / (board games) position: the configuration of pieces on the board and what this implies

a musical arrangement

arrange music

curve

constituency - (a district represented by an elected official; the voters of such a district)

drugstore (no prescription required: over-the-counter medicines only) / pharmacy (prescription required)

depolarization

electrode

general situation; the whole point, the big picture (totality of a situation)