Copious

abundant; plentiful

Tenacious

tough; stubborn; not letting go

Surreptitious

done or acting in a secret, sly manner

Voracious

an insatiable appetite for an activity or pursuit; eager to consume great amounts of food

Officious

interfering; intrusive; eager in offering unwanted services or advice

Spurious

not genuine; false

Onerous

troublesome or oppressive; burdensome

Gregarious

seeking and enjoying the company of others; sociable

Pious

devout or virtuous; holy

Scrupulous

careful of small details; honest; conscientious