Godan verb with 'ru' ending, Intransitive verb
to climb; to clamber (over, up); to scramble (up); to scale; to claw one's way up
私は鳩たちがその箱の上によじ登ったご褒美に餌を与えた。I rewarded my pigeons with food for climbing onto the box.
Also written 攀じ登る【よじのぼる】、攀じ上る【よじのぼる】