A galdr (plural galdrar) or ġealdor (plural ġealdru) refers to a spell or incantation in Old Norse and Old English respectively; these were usually performed in combination with certain rites.^[1]

Old Norse: galdr and Old English: ġealdor or galdor are derived from the reconstructed Proto-Germanic *galdraz, meaning a song or incantation.^[2][3] The terms are also related by the removal of an Indo-European -tro suffix to the verbs Old Norse: gala and Old English: galan, both derived from Proto-Germanic *galaną, meaning to sing or cast a spell.^[4][5] In Old High German the -stro suffix produced galster instead.^[6]

The German forms were Old High German galstar and Middle High German (MGH) galster "song, enchantment" (Konrad von Ammenhausen Schachzabelbuch 167b), surviving in (obsolete or dialectal) Modern German Galsterei (witchcraft) and Galsterweib (witch).

From these terms are descended words such as the Icelandic verb að gala "to sing, call out, yell", Middle English: galder "magic" and as a component of nightingale (from nihtegale), related to ġiellan, the verb ancestral to Modern English yell.^[7][8] The words are also cognate with Dutch gillen "to yell, scream".

Some incantations were composed in a special meter named galdralag.^[9] This meter was similar to the six-lined ljóðaháttr, also used for ritual, but added at least one more C-line.^[10] Diverse runic inscriptions suggest informal impromptu methods. Another characteristic is a performed parallelism,^[10] see the stanza from Skirnismál, below.

A practical galdr for women was one that made childbirth easier,^[9] but they were also notably used for bringing madness onto another person, whence modern Swedish galen meaning "mad",^[11] derived from the verb gala ('to sing, perform galdr').^[12] 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.^[11] Examples of this can be found in Grógaldr and in Frithiof's Saga.^[11] In Grógaldr, Gróa chants nine (a significant number in Norse mythology) galdrar to aid her son, and in Buslubœn, the schemes of king Ring of Östergötland are averted.^[13]

It is also mentioned in several of the poems in the Poetic Edda, and for instance in Hávamál, where Odin claims to know 18 galdrar.^[1] For instance, Odin mastered galdrar against fire, sword edges, arrows, fetters and storms, and he could conjure up the dead and speak to them.^[14][15] There are other references in Skírnismál,^[1] where Skirnir uses galdrar to force Gerðr to marry Freyr^[13] as exemplified by the following stanza:

A notable reference to the use of galdrar is the eddic poem Oddrúnargrátr, where Borgny could not give birth before Oddrún had chanted "biting galdrar"^[9] (but they are translated as potent charms, by Henry Adams Bellows below):

In Beowulf, ġealdru are used to protect the dragon's hoard that was buried in a barrow:

It was performed by both women and men.^[9] Some scholars have proposed they chanted it in falsetto (gala).^[9][11]

• Grógaldr
• Runic magic
• Icelandic magical staves
• Seiðr

• Schön, Ebbe. (2004). Asa-Tors hammare, Gudar och jättar i tro och tradition. Fält & Hässler, Värnamo. ISBN 91-89660-41-2.
• Steinsland, G. & Meulengracht Sørensen, P. (1998): Människor och makter i vikingarnas värld. ISBN 91-7324-591-7.