semi-sweet

/S EH1 M IY0 S W IY0 T/
adjective
  1. 1

    Partially sweet or sweetened, but having a distinct bitter component. Especially used to describe dark chocolate that is much less sugary than milk chocolate.

Source: https://en.wiktionary.org/wiki/semi-sweet, https://en.wiktionary.org/wiki/semisweet