Middle English hert, from Old English heorot "hart, stag, male of the red deer," from Proto-Germanic *herutaz (source also of Old Saxon hirot, Old Frisian and Dutch hert "stag, deer," Old High German hiruz, Old Norse hjörtr, German Hirsch "deer, stag, hart"), perhaps from PIE *keru-, extended form of root *ker- (1) "horn; head." For vowel change, see marsh.
In later times, a male deer after its fifth year, when the crown antler has appeared. The female is a hind (n.).
Old English ford "shallow place where water can be crossed," from Proto-Germanic *furdu- (source also of Old Frisian forda, Old High German furt, German Furt "ford"), from PIE *prtu- "a going, a passage" (source also of Latin portus "harbor"), from root *per- (2) "to lead, pass over." The line of automobiles (company founded 1903) is named for U.S. manufacturer Henry Ford (1863-1947).
<a href="https://www.etymonline.com/word/Hertfordshire">Etymology of Hertfordshire by etymonline</a>
Harper, D. (n.d.). Etymology of Hertfordshire. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/Hertfordshire