Synonyms:
- Herculean,
- abstruse,
- acanthoid,
- acanthous,
- acicular,
- acuate,
- aculeate,
- aculeiform,
- acuminate,
- acute,
- arduous,
- barbed,
- brutal,
- complex,
- cornuted,
- critical,
- cusped,
- cuspidate,
- delicate,
- demanding,
- difficile,
- difficult,
- exacting,
- formidable,
- hairy,
- hard,
- hard-earned,
- hard-fought,
- hispid,
- horned,
- horny,
- intricate,
- jawbreaking,
- knotted,
- knotty,
- laborious,
- mean,
- mucronate,
- needle-pointed,
- needle-sharp,
- nettlesome,
- no picnic,
- not easy,
- operose,
- pointed,
- prickly,
- pronged,
- rigorous,
- rough,
- rugged,
- set with thorns,
- severe,
- sharp-pointed,
- spiculate,
- spiked,
- spiky,
- spined,
- spinous,
- steep,
- strenuous,
- tapered,
- tapering,
- thorny,
- ticklish,
- tined,
- toilsome,
- toothed,
- tough,
- tricky,
- unbated,
- uphill,
- wicked