As a noun tumor
is a tumor (oncology, pathology: an abnormal growth).
As an adjective tumorless is
Other Comparisons: What's the difference?
* tumour (Commonwealth)
(oncology, pathology) An abnormal growth; differential diagnosis includes abscess, metaplasia, and neoplasia.
is the standard modern spelling elsewhere.
* (an abnormal growth) neoplasm
* (an abnormal growth) adenoma, granuloma
* See also