#1-When the going gets tough

difficult to understand

Abby found her professor's lecture on non Euclidian geometry abstruse; she doubted anyone else in class understood it either

emotionally hardened; unfeeling

Callie's callous remark about her friend's cluttered room really hurt his feelings

intricate; complex

The directions were so convoluted that we became hopelessly lost.

a puzzle, mystery, or riddle

The emu was an enigma; you culd neber tell what it was thinking.

difficult to fathom or understand; impenetrable

The ancient poet's handwriting was so inscrutable, that even the most prominent Latin scholars could not read the manuscripts.

inclined to keep silent; reserved

Rosanna's reticent behavior caused the interviewer to think her incapable of conversing with other students.

unemotional; serious

Mr.Estado was well known for his staid demeanor; he stayed calm even when everyone else celebrated the team's amazing victory.