This is the 5840th most frequent Japanese word.
びく
"びく" refers to a fishing creel or basket used to carry caught fish.
The word 'びくと' conveys a subtle twitch-like movement, often due to a reaction.
触るとカエルがびくと動いた。
When I touched it, the frog twitched.
Here, 'びくっと' expresses the sudden small movement due to surprise or fear.
その音にびくっとした。
I flinched at that sound.
In this case, 'びくびく' describes a state of being overly nervous or afraid, often unnecessarily.