fosse is also spelled foss (also meaning ditch), which gives you the orthoepy. it's used mostly these days in historical or archeological contexts. another earlier sense was 'cart-rut', which has come up here before.

1969 C. Cochrane Lost Roads of Wessex i. 14 No Roman way has been listed as located between Salisbury and the southern part of the Fosse [One of the four great Roman roads in Britain, so called from the ditch or fosse on each side; it probably ran from Axminster to Lincoln, via Bath and Leicester]. Ibid. vi. 119 For a short distance the Roman quarrystone paving of the Foss was intact. [Cochrane was taking no chances with the spelling!]

hithe/hythe - A port or haven; esp. a small haven or landing-place on a river. Now obsolete except in historical use, and in place-names, as Hythe, Rotherhithe, Lambeth (orig. Lamb-hithe), Hythe Bridge at Oxford, Bablock Hithe on the Thames above Oxford.

[OED]