A lingua ignota (Latin for "unknown language") was described by the 12th-century abbess Hildegard of Bingen, who apparently used it for mystical purposes.

[1] St. Hildegard partially described the language in a work titled Ignota lingua per simplicem hominem Hildegardem prolata, which survived in two manuscripts, both dating to ca.

Grammatically it appears to be a partial relexification of Latin, that is, a language formed by substituting new vocabulary into an existing grammar.

[4] However, in the 21st century it is assumed that Lingua ignota was devised as a secret language; like Hildegard's "unheard music", she would have attributed it to divine inspiration.

The first 30 entries are (after Roth 1880): Nominal composition may be observed in peueriz "father" : hilz-peueriz "stepfather", maiz "mother" : hilz-maiz "stepmother", and scirizin "son" : hilz-scifriz "stepson", as well as phazur : kulz-phazur.