1650s, "fleshy excrescence," Medical Latin, from Latinized form of Greek sarkoma "fleshy substance" (Galen), from sarkoun "to produce flesh, grow fleshy," from sarx (genitive sarkos) "flesh" (see sarcasm) + -oma. Meaning "harmful tumor of the connective tissue," more or less malignant, is from 1804 (Abernethy). Related: Sarcomatous.

"a propagating malignant tumor," 1721, from Latin carcinoma, from Greek karkinoma "a cancer," from karkinos "a cancer," literally "a crab" (see cancer) + -oma. Related: Carcinomatous. The classical plural is carcinomata.

"tumor produced by enlargement or new formation of blood vessels," 1867, medical Latin, from angio- + -oma. Related: Angiomatous.

"encysted tumor," 1706, medical Latin, from Greek atheroma, from athērē "groats, porridge," in reference to the matter inside; a word of unknown origin. It is sometimes said to be perhaps related to athēr "chaff," but Beekes finds this "neither formally nor semantically plausible." Pliny calls it an Egyptian word. For the ending, see -oma. Related: Athermatous (1670s).

"large, natural community of plants and animals," 1916, formed from Greek bios "life" (from PIE root *gwei- "to live") + -ome, an Anglicization of Greek -(o)ma, neuter noun suffix (see -oma). Probably coined by U.S. ecologist Frederic E. Clements.

1640s, "state paper, official document," from Latin diploma (plural diplomata) "a state letter of recommendation," given to persons travelling to the provinces, "a document drawn up by a magistrate," from Greek diploma "licence, chart," originally "paper folded double," from diploun "to double, fold over," from diploos "double" (see diplo-) + -oma, suffix forming neuter nouns and nouns that indicate result of verbal action (see -oma).

The main modern use is a specialized one, "a writing under seal from competent authority conferring some honor or privilege," especially that given by a college conferring a degree or authorizing the practice of a profession (1680s in English).

The plural is always -mas in the ordinary sense (certificate of degree &c.), though -mata lingers in unusual senses (state paper &c.) as an alternative. [Fowler]

Compare diplomacy, diplomatic.

1711, "pertaining to official or original documents, texts, or charters," from Modernl Latin diplomaticus (1680s), from diplomat-, stem of Latin diploma "a state letter of recommendation," given to persons travelling to the provinces, "a document drawn up by a magistrate," from Greek diploma "a licence, a chart," originally "paper folded double," from diploun "to double, fold over," from diploos "double" (see diplo-) + -oma, suffix forming neuter nouns and nouns that indicate result of verbal action (see -oma).

Meaning "pertaining to or of the nature of diplomacy; concerned with the management of international relations" is recorded by 1787, apparently a sense evolved in 18c. from the use of diplomaticus in Modern Latin titles of collections of international treaties, etc., in which the word referred to the "texts" but came to be felt as meaning "pertaining to international relations."

In the general sense of "tactful and adroit, skilled in negotiation or intercourse of any kind" it dates from 1826. Diplomatic immunity is attested by 1849. Related: Diplomatically.

type of brain tumor, 1870, medical Latin, literally "glue tumor," from Greek glia "glue" (from PIE root *glei- "clay," also forming words with a sense of "to stick together;" see clay) + -oma. Related: Gliomatosis; gliomatous.

"granulated tissue produced by certain diseases," from Latin granulum "granule" (see granular) + -oma, on model of glaucoma, etc.

also haematoma, 1826, from hemato- + -oma.