Galdr
Etymology. The Old Norse word ' is derived from a word for singing incantations, ' (Old High German and Old English: ') with an Indo-European "-tro" suffix. In Old High German the ' suffix produced "" instead. The Old English forms were ' ~ ' "spell, enchantment, witchcraft", and the verb ' meant "sing, chant". It is contained in "nightingale" (from '), related to ', the verb ancestral to Modern English "yell"; compare also the Icelandic verb ' "to sing, call out, yell" and Dutch "" "to yell, scream". The German forms were Old High German ' and MHG ' "song, enchantment" (Konrad von Ammenhausen "Schachzabelbuch" 167b), surviving in (obsolete or dialectal ) Modern German ' (witchcraft) and ' (witch). Practice. Some incantations were composed in a special meter named "". This meter was similar to the six-lined , also used for ritual, but added at least one more C-line Diverse runic inscriptions suggest informal impromptu methods. Another characteristic is a performed parallelism, see the stanza from "Skirnismál", below. A practical for women was one that made childbirth easier, but they were also notably used for bringing madness onto another person, whence modern Swedish "" meaning "mad", derived from the verb "gala" ('to sing, perform galdr'). Moreover, a master of the craft was also said to  be able to raise storms, make distant ships sink, make swords blunt, make armour soft and decide victory or defeat in battles. Examples of this can be found in "Grógaldr" and in "Frithiof's Saga". In "Grógaldr", Gróa chants nine (a significant number in Norse mythology) to aid her son, and in "Buslubœn", the schemes of king Ring of Östergötland are averted. It is also mentioned in several of the poems in the "Poetic Edda", and for instance in "Hávamál", where Odin claims to know 18 . For instance, Odin mastered galdrar against fire, sword edges, arrows, fetters and storms, and  he could conjure up the dead and speak to them. There are other references in "Skírnismál", where Skirnir uses to force Gerðr to marry Freyr as exemplified by the following stanza: A notable reference to the use of is the eddic poem "Oddrúnargrátr", where Borgny could not give birth before Oddrún had chanted "biting " (but they are translated as "potent charms", by Henry Adams Bellows below):