IPA: /hɪrˈʌntu/
KK: /hɪrˈʌntu/
To this point or place; up to this time or moment.
The committee has agreed to the terms set forth in the document hereunto attached.
Hereunto is formed from "here" (from Old English "hēr", meaning in this place) and "unto" (from Old English "untō", meaning to or towards). The word "hereunto" means to this place or to this point in relation to something previously mentioned.
Think of 'here' as indicating a specific place and 'unto' as meaning 'to' — together, they help you remember that 'hereunto' refers to a direction or reference to this specific place.