The Viking name for the native people they encountered in their journey to Vinland
It's not known exactly where Vinland or the other lands described in the sagas (Helluland and Markland) actually were -- Vinland could fit anywhere from Newfoundland to Cape Cod --, so the exact identity of the Skraelings is also in doubt. Their large canoes (under which three could sleep), their "small" nature (one manuscript has "swarthy" instead), and their food (beast marrow mixed with blood, i.e. pemmican) fairly clearly mark them out as Native American (Indians) rather than Inuit (Eskimos).
When Viking settlers under Eric the Red reached Greenland in 985, it was uninhabited, though they found traces of habitation, stone tools, and broken canoes, such as they had seen among the Skraelings of Vinland. This is described by Ari Thorgilsson writing around 1130 in the Libellus Islandorum. Several centuries later the Inuit returned to Greenland, attacking the Norse colonies in the 1370s. These people were also called Skraelings by the settlers, and the name is still in use in modern south Greenlandic Inuktitut, in the form Kalaleq.
The nearest approach the Inuktitut language could make to the syllables would have been *Sakaraleq. At an early stage the first syllable was lost, or perhaps the Inuit just simplified the skr- from the beginning. A 1427 map ascribes the name Careli to the natives of Greenland. Hans Egede, who in 1739 published the first dictionary of Greenlandic Inuktitut, recorded the form Karaleq. Since then normal sound changes have made it Kalaleq.
In Old Norse it was pronounced with the first syllable as in "scram". In modern Icelandic it's pronounced with "scry", and it means "churl" or "wretch"; in modern Norwegian it means "weakling". It's unclear where it comes from: perhaps a root for "scream", or one for "shrink, cower". But no such word is known in Old Norse.
The Norse plural is Skrælingar, and the place-name Skrælingaland was used.