egwyddor or abiéc
No because x isn't in the welsh alphabet
The Welsh alphabet consists of 28 letters.
No.
The letters K, Q, V and Z do not appear in the Welsh alphabet.
It is unlikely as there is no letter J in the Welsh alphabet. There are several versions in Welsh. Siân is most common. Also Siani.
The Welsh word for Toxic is: Gwenwynig
The word 'fern' is not a Welsh word and has no meaning. The Welsh word for 'a fern' is 'rhedynen'.
The Welsh word for mum is mam.The Welsh word for dad is dad.
The Welsh word for 'decibel' is desibel.
The Welsh word for Excellent is ardderchog, it is also the welsh for fantastic.
The Welsh word for planet is 'planed' (plural - planedau)
The Welsh word for thunder is "taranu."