Surely one of the most successful groups of animals in the history of this planet. There are arachnids on every continent (except Antarctica, obviously). Arachnids include spiders, scorpions, mites, ticks and the like. Though it is very rare for soft-bodied animals to survive, in fossil form, the oldest known fossil spider is 380 million years old, and there are even older fossil scorpions and sea scorpions known. Whenever I watch a tarantula or scorpion I can't help feeling I'm being given a viewpoint on an early age of life on this planet.
An example of an arachnid: a tarantula, a member of the oldest group of spiders which did not spin webs, merely used silk to line their burrows.
by Stormsworder November 16, 2006
Fucking disgusting eight-legged abominations created by god to scare the fuck out of you by appearing out of fucking nowhere and disappearing when you get back with your chancla
"Holy fuck I just saw a spider (arachnid),"
*gets chancla*
"Fuck it's gone,"
*fucking moves out*
by snickersnigger March 27, 2018
A more nuanced take on ‘not here to fuck spiders’. A classic Australianism expressing that things of little consequence or excessive moderation are not worthy to be undertaken.

Further context, similar to ‘having bigger fish to fry’.
“Hey Ellis, last drinks just got called. Pint of pale and mezcal chaser?” says Toph.
“Not here to fornicate with arachnids.” he replies in support of the offer.
by Kiz... December 25, 2020
Various spiders found in Level 8 of the Backrooms.
The Arachnids of Level 8 are all venomous.
by MaybeARealWord January 13, 2022
Rip off of spider man, if you like this word your gay and a mistake, if you are this word your the worst ever there is no word that explains you
Wow that arachnid boy is so gay and retarded, ew he looks like an arachnid boy
by Landon <3 January 26, 2022