A Grammatical Dictionary of Botanical Latin

Cancer, gen. sg. cancri (also canceris) (s.m. [sometimes n.] II), acc. sg. cancrum, dat. & abl. sg. cancro;

1. cancer, gen.sg. cancri (s.m.II), abl.sg. cancro: a lattice or barrier (Glare); a lattice, grille, grid or barrier; see trellis.

2. A crab; the constellation Cancer (“which the sun enters in the middle of the summer solstice; hence associated with summer heat; the name applied to various diseases now distinguished, including malignant tumors, cankers” (Glare); a cancerous disease; see ‘crab;’ see ‘-oma, in Greek endings;’ see tumor;

NOTE: classically: irregular nom. pl. canceres], gen. pl. cancrorum, [irregular acc. pl. canceres], dat. & abl. pl. cancris; from an ancient root meaning to be hard; a crab, river or sea-crab, lobster: in medicine, an ulcerating sore, malignant tumor, a cancer; a canker; the Crab, sign of the zodiac (Ovid: malum immedicabile cancer: as a neuter).

As a Decl. II noun ending in -er: cancer, gen.sg. cancri:

        sg.      pl.
Nom.  cancer   cancri
Gen.  cancri   cancrorum
Dat.  cancro   cancris
Acc.  cancrum  cancros
Abl.  cancro   cancris

Cancer, gen.sg. cancri (s.m.II), the type genus of the Cancridae, a large family of crabs [Cancr- + -idae].

Carcinoma,-atis (s.n.III), abl.sg. carcinomate: “a disease in trees when the bark separates, an acrid sap exuding and ulcerating the surrounding parts” (Lindley) [> L. carcinoma,-atis (s.n.III) = Gk. karkinOma, a cancerous ulcer, a cancer (Lewis & Short)].

NOTE: GREEK [25 BC - 50 AD) translated ‘karkinos’ into cancer, the Latin word for crab or crayfish. In the 2nd century AD, the Greek physician Galen used oncos (Greek for ‘swelling’) to describe all tumours, reserving Hippocrates' term carcinos for malignant tumours. Galen also used the suffix -oma to indicate cancerous lesions.” [no citation] [> Gr. karkinos (s.m.II): a crab, = L. cancer; “the Crab, as a sign in the zodiac” (Liddell & Scott)].

Gangraena,-ae (s.f.I): “a disease ending in putrid decay” (Lindley) [> L. gangraena,-ae (s.f.I) > Gk. gangraina [two gammas], a cancerous, eating ulcer on the body, a gangrene” (Lewis & Short).

cancriformis,-e (adj.B), q.v.: in the form or shape of a crab; of a tumor or cancer.