The languages peculiar to the Orcs in the works of J.R.R. Tolkien. The Orcs had adopted the languages of those around them but changed and corrupted. They quickly split into fissiparous tribes with no comprehension of each other's tongues. In the third age they, like most other peoples of Middle-earth, used the Common Speech for communication between groups.
At first Sauron had devised the Black Speech hoping that all his creatures would use it, but failed in this. Only Sauron and the Nazgûl spoke it. However some Black Speech words were commonly used in Orkish. One such is ghâsh 'fire', ominously heard by the Fellowship in Moria. Others were uruk 'orc', mainly used of the Uruk-hai or Great Orcs, and Lugbúrz 'Dark Tower' (cf. burzum 'darkness' in the Ring-rhyme).
The lesser orcs were called snaga 'slave', especially by the Uruk-hai. The word for 'old man' was sharkû, later adapted into the form Sharkey as the common name for Saruman when he was the ruler of the Shire. The word tark 'man of Gondor' is derived from Quenya tarcil. At least two Orkish personal names occur, Uglúk and Grishnákh.
The only sentence known in Orkish is Grishnákh's muttered curse (The Two Towers, chap. III, p.47): Uglúk u bagronk sha pushdug Saruman-glob búbhosh skai. Orkish is said to have been very good for cursing, though not very expressive in other respects. This is not translated in The Lord of the Rings, but unpublished papers show that it meant 'Uglúk to the dungheap with stinking Saruman-filth, pig-guts, gah!'.
This fragment shows that Orkish is very different grammatically from Black Speech, although they have similar phonetics. Black Speech had postpositions (ishi 'in' in the Ring-inscription) while Orkish has prepositions u 'to' and sha 'with'. Black Speech was highly inflected (durb-at-ul-ûk perhaps 'rule-INF-them-all') whereas Orkish shows only compounding of simple roots, and possibly a participle (pushdug from a verb push 'stink'?).
Tolkien used the English spelling Orkish, not Orcish. As with Sindarin, he is slightly inconsistent in his use of accents: he actually writes Lugbúrz but could have used Lugbûrz. The difference is not significant.
It is said that Orcs pronounced their R as uvular, as in French. (Tolkien disliked this sound.) If there were many other words in use with the velar sound GH, which occurred in Black Speech, then we have an interesting (and very rare in modern Earthly languages*) contrast between velar and uvular fricatives.
* Thanks to Cletus the Foetus for pointing out Dutch as an example. I always wondered about the Dutch.