orifice

/AO1 R AH0 F AH0 S/
noun
  1. 1

    A mouth or aperture, such as of a tube, pipe, etc.; an opening.

    โ€œthe orifice of an artery or vein; ย  the orifice of a wound; ย  the vagina and other orificesโ€

Source: https://en.wiktionary.org/wiki/orifice