1. (superl.) Full of thorns or spines; rough with thorns; spiny; as, a thorny wood; a thorny tree; a thorny crown.

2. (superl.) Like a thorn or thorns; hence, figuratively, troublesome; vexatious; harassing; perplexing.

Herculean abstruse acanaceous acanthoid aciculate aculeolate arduous barbed barbellate brambly briery bristly brutal complex complicated controversial critical delicate demanding difficile difficult exacting formidable hairy hard hard-earned hard-fought intricate involved jawbreaking knotted knotty laborious mean muricate nasty nettlesome no picnic not easy operose painful pricking prickly pricky problematic rigorous rough rugged set with thorns setaceous setose severe spiculate spiculose spiked spinous spiny steep sticky stinging strenuous tangled thistly ticklish toilsome tough tricky troublesome uphill vexatious wicked worrying