It forms all or part of: hali-; halide; halieutic; halite; halo-; halogen; sal; salad; salami; salary; saline; salmagundi; salsa; salsify; salt; salt-cellar; saltpeter; sauce; sausage; silt; souse.
It is the hypothetical source of/evidence for its existence is provided by: Greek hals "salt, sea;" Latin sal, Old Church Slavonic soli, Old Irish salann, Welsh halen, Old English sealt, German Salz "salt."
The name is from Latin halcyon, alcyon, from Greek halkyon, variant (perhaps a misspelling) of alkyon "kingfisher," a word of unknown origin. The explanation that this is from hals "sea; salt" (see halo-) + kyon "conceiving," present participle of kyein "to conceive," literally "to swell" (see cumulus) probably is ancient folk-etymology to explain a loan-word from a non-Indo-European language. Identified in mythology with Halcyone, daughter of Aeolus, who when widowed threw herself into the sea and became a kingfisher.
1610s, "bright cloud surrounding a divine or sacred personage," from Latin nimbus "cloud," which is perhaps related to nebula "cloud, mist" (from PIE root *nebh- "cloud"). In art, the meaning "halo around the head of a representation of a divine or sacred person" is by 1727. Figurative use is by 1860. Compare aureole.
The nimbus of God the Father is represented as of triangular form, with rays diverging from it on all sides, or in the form of two superposed triangles, or in the same form (inscribed with the cross) as that of Christ. The nimbus of Christ contains a cross more or less enriched; that of the Virgin Mary is a plain circle, or occasionally a circlet of small stars, and that of angels and saints is often a circle of small rays. When the nimbus is depicted of a square form, it is supposed to indicate that the person was alive at the time of delineation. [Century Dictionary]
early 12c. as an adjective, seinte, "holy, divinely inspired, worthy of worship," used before proper names (Sainte Marian Magdalene, etc.), from Old French saint, seinte "holy, pious, devout," from Latin sanctus "holy, consecrated," past participle of sancire "consecrate" (see sacred). It displaced or altered Old English sanct, which is directly from Latin sanctus.
From an adjective prefixed to the name of a canonized person, it came to be used in English by c. 1200 as a noun, "a specific canonized Christian," also "one of the elect, a member of the body of Christ, one consecrated or set apart to the service of God," also in an Old Testament sense "a pre-Christian prophet."
It is attested by late 13c. as "moral or virtuous person, one who is pure or upright in heart and life."
The adjectives also were used as nouns in Late Latin and Old French: "a saint; a holy relic." The Latin word also is the source of Spanish santo, santa, Italian san, etc., and also ultimately the source of the word in most Germanic languages (Old Frisian sankt, Dutch sint, German Sanct).
Perhaps you have imagined that this humility in the saints is a pious illusion at which God smiles. That is a most dangerous error. It is theoretically dangerous, because it makes you identify a virtue (i.e., a perfection) with an illusion (i.e., an imperfection), which must be nonsense. It is practically dangerous because it encourages a man to mistake his first insights into his own corruption for the first beginnings of a halo round his own silly head. No, depend upon it; when the saints say that they—even they—are vile, they are recording truth with scientific accuracy. [C.S. Lewis, "The Problem of Pain," 1940]