We don't have synonyms for nidering yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are widening, ordering and hindering.
(n) :
(archaic) Alternative form of niddering (synonym of nithing). [(archaic) Synonym of nithing (“a coward, a dastard; a wretch”).]
(adj) :
(archaic) Alternative form of niddering (synonym of nithing). [(archaic) Synonym of nithing (“cowardly, dastardly; notoriously evil or wicked; infamous”).]
(n) :
(archaic) Alternative form of niddering (synonym of nithing). [(archaic) Synonym of nithing (“a coward, a dastard; a wretch”).]
(adj) :
(archaic) Alternative form of niddering (synonym of nithing). [(archaic) Synonym of nithing (“cowardly, dastardly; notoriously evil or wicked; infamous”).]