Question: In Tetrabiblos, what does Hyleg mean?
Context: The grand mean is the mean of the means of several subsamples, as long as the subsamples have the same number of data points.  For example, consider several lots, each containing several items.  The items from each lot are sampled for a measure of some variable and the means of the measurements from each lot are computed.  The mean of the measures from each lot constitutes the subsample mean.  The mean of these subsample means is then the grand mean. Tetrabiblos (Τετράβιβλος ) 'four books', also known in Greek as Apotelesmatiká (Ἀποτελεσματικά ) "Effects", and in Latin as Quadripartitum "Four Parts", is a text on the philosophy and practice of astrology, written in the 2nd century AD by the Alexandrian scholar Claudius Ptolemy ( AD 90– AD 168). Western astrology is the system of astrology most popular in Western countries.  Western astrology is historically based on Ptolemy's "Tetrabiblos" (2nd century CE), which in turn was a continuation of Hellenistic and ultimately Babylonian traditions. In mathematics, the Riesz mean is a certain mean of the terms in a series.  They were introduced by Marcel Riesz in 1911 as an improvement over the Cesàro mean .  The Riesz mean should not be confused with the Bochner–Riesz mean or the Strong–Riesz mean. Nosferatu molango (previously placed in the genus "Herichthys"), also known as Aztec Cichlid, is a species of cichlid endemic to the "Laguna Azteca", in the headwaters of the Rio Moctezuma (Rio Panuco Basin), in the municipality of Molango, state of Hidalgo, Mexico at 1,270 meters above sea level.  It is distinguished from other species of the genus in "having a slender (slightly broader than long), well-spaced, unicuspid and conical, posterior slightly flattened, indented lower pharyngeal plate (instead of having large molars), with 2 rows of 8–9 medium-sized, lightly pigmented molars that flank the midline; 11–13 nonenlarged conic teeth along the posterior margin.  Distinguished from all other species in the genus by a combination of the following characters: predorsal contour deep and nonacute, which is not concave before the eye; head short (mean 35%, SD 3%), rostral tip to the pectoral fin origin distance (mean 33%, SD 1%); caudal peduncle short (mean 15%, SD 1%) and deep (mean 16%, SD 1%), long anal fin (origin to hypural base distance; mean 40%, SD 1%); wide preorbit (mean 30%, SD 3%); eye small (mean 21%, SD 2%).  Peritoneum is uniformly very dark." Cornelius (or Cornelio) Gemma (28 February 1535 – 12 October 1578) was a physician, astronomer and astrologer, and the oldest son of cartographer and instrument-maker Gemma Frisius.  He was a professor of medicine at Catholic University of Leuven, and shared in his father's efforts to restore ancient Ptolemaic practice to astrology, drawing on the "Tetrabiblos". In mathematics and statistics, the quasi-arithmetic mean or generalised "f"-mean is one generalisation of the more familiar means such as the arithmetic mean and the geometric mean, using a function formula_1.  It is also called Kolmogorov mean after Russian mathematician Andrey Kolmogorov. In the field of differential geometry in mathematics, mean curvature flow is an example of a geometric flow of hypersurfaces in a Riemannian manifold (for example, smooth surfaces in 3-dimensional Euclidean space).  Intuitively, a family of surfaces evolves under mean curvature flow if the normal component of the velocity of which a point on the surface moves is given by the mean curvature of the surface.  For example, a round sphere evolves under mean curvature flow by shrinking inward uniformly (since the mean curvature vector of a sphere points inward).  Except in special cases, the mean curvature flow develops singularities. In Hellenistic astrology, the hyleg is the Persian-Arabic term for the planet with the greatest essential dignity in five important natal chart positions (according to Ptolemy's "Tetrabiblos"): Abu Yahya Ibn al-Batriq (working 796 - 806) was a Syrian scholar who pioneered the translation of ancient Greek texts into Arabic, a major early figure in the transmission of the Classics at the close of Late Antiquity.  He translated for Al-Mansur the major medical works of Galen and Hippocrates, and also translated Ptolemy's "Tetrabiblos".
Answer: hyleg is the Persian-Arabic term for the planet