The OED says that in English bats "were formerly classed as birds" and gives the quotation from 1340, "Bringen her a nihte-bird . a bakke . or an oule."
In Old English a bat was a hreaðemūs — "The first element may represent the stem of Old English hrēran to move, to shake, to agitate". Later this became rearmouse or reremouse, which survived in some rural dialects and in heraldry.
The word bakke comes from a Scandinavian language (perhaps Danish) and first appears in the 14th century; this became bat by the late 16th century.
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In Old English a bat was a hreaðemūs — "The first element may represent the stem of Old English hrēran to move, to shake, to agitate". Later this became rearmouse or reremouse, which survived in some rural dialects and in heraldry.
The word bakke comes from a Scandinavian language (perhaps Danish) and first appears in the 14th century; this became bat by the late 16th century.