The Delta Quadrant cytoplasmic lifeform language was the incredibly complex language of an unnamed non-humanoid cytoplasmic lifeform encountered by the USS Voyager in 2375.
Captain Kathryn Janeway attempted to translate the language by instructing the computer to assign symbols to all the different tones in a message they had received from this species in order to ascertain their meaning. It proved futile when it turned out that there were over 10,000 different sounds in what was only one section of the entire message. In the end the language proved indecipherable, its complexity far beyond the capabilities of the Federation to translate at the time of the encounter.
The cytoplasmic lifeforms however could understand the Starfleet crew, probably trough use of a universal translator. It is unknown if they understood the crew through the use of the Federation universal translator or a similar device of their own. (VOY: "Nothing Human")
The language consisted of a series of high pitched shrieks and screams and it was rather annoying and uncomfortable to listen to for humanoids.