Sundor-cýþþ[u]

According to the Old English Dictionary:

sundor-cýþþ[u]

f. Special, private knowledge or acquaintance, intimacy:?-Riht is ðæt mynecena ǽnige sundorcýþþe tó woruldmannum nabban, L. I. P. 15; Th. ii. 322, 34. sundor-cyþþu