The Latin word feudum is translated as Holding in the Phillimore edition, though more commonly as fief.
By convention, the term fief is used to describe all the manors held by a tenant-in-chief in one county. These would be described in a single block, or chapter, unless the tenant-in-chief was a minor landholder in which case they were described in part of a collective fief towards the end of the county. All the county fiefs held by a tenant-in-chief constituted his Honour. Honour and fief are both conventional, not technical terms, and they are sometimes used interchangeably.
The usage in Domesday Book is even looser: feudum was applied to Honours, fiefs, and even to single manors, both before and after the Conquest. Many historians would regard a pre-Conquest feudum as an anachronism.
For more detail, see Sir Fredrick Pollock and F.W. Maitland, The history of English law before the time of Edward I (second edition, 1898); and Susan Reynolds, Fiefs and vassals: the medieval evidence reinterpreted (1994).