How did the bat get its name?

Answer 1

The animal:

The term 'bat' describing a flying mammal first appeared in Middle English in the 1500s as 'bakke'; this term was still in general use in English during the 1570s.

'Bakke' came into English from the Scandinavian (Old Swedish/Old Norse) term, 'nattbakka' meaning 'evening or night bat', sharing origins with Old Norse 'leorblaka'meaning '(a) leather flapper', which makes sense, given the leathery wings of bats. It is possible the 'k' in these words changed to 't' in English through confusion with the Latin 'blatta' (nocturnal insect, or moth).

Before the 1500s the creature was called, in Old English, 'hreremus', from 'hreran', (to shake), also used as an offensive term to describe an old woman.

Sports equipment:

The club or stick called a 'bat' is from Late Old English, 'batt', and its use to describe sporting equipment is first recorded in 1706.

Before that it is thought to be related to a Celtic term for a staff or cudgel, 'bata', formed under the influence of Old French, and in turn from Latin 'battre' (to beat or strike): all ultimately attributed to Indo-European (or Proto-Indo-European: PIE), the unattested prehistoric catch-all parent base of most European and some Asian languages.