Vyaghata is the thirteenth nityayoga, and its name means a beating, an obstruction, or a striking blow. It is one of the inauspicious yogas, associated with conflict and setback, and the panchanga counts it among the configurations to be avoided for auspicious undertakings. Like the others it is derived from the combined longitude of Sun and Moon divided into twenty-seven equal parts, advancing through the month. In selecting a muhurta an astrologer avoids the malefic yogas, and Vyaghata, with its sense of a thwarting blow, is one the tradition treats with caution. These are the conventions of the calendar tradition, which assigns each of the twenty-seven yogas a fixed favourable or unfavourable nature; the astronomical basis is only the summed motion of the two lights.
Vyaghata combines the prefix vi, apart or asunder, with ghata, a striking or a blow, giving a sense closer to a shattering or dispersing blow than to an ordinary strike, which fits the yoga's classical association not merely with conflict but with setbacks that scatter or undo what has already been accomplished, a nuance the general gloss "a beating, an obstruction" given above does not fully capture. The same root ghata also names, in an entirely unrelated everyday sense, a clay water pot, and Sanskrit dictionaries list both senses, the blow and the pot, as separate developments from an underlying root concerned with striking or forming by striking, the latter presumably from the potter's shaping blows.