Etgar (אתגר) means challenge. It is a noun but by saying etgary, it becomes an adjective. It can also be used as the verb le'atger (לאתגר), meaning to challenge someone.
There are even people who have etgar as their proper name. Etgar Keret is a well-known Israeli author who writes screenplays, poems, songs, and comics.
Learning Hebrew is a challenge, but one that will give you an enormous sense of accomplishment. We have found that our students love challenges!