(s)rugged, toughvery difficult; severely testing stamina or resolution“a rugged competitive examination”, “the rugged conditions of frontier life”, “the competition was tough”, “it's a tough life”, “it was a tough job”
(s)sturdy, toughsubstantially made or constructed“sturdy steel shelves”, “sturdy canvas”, “a tough all-weather fabric”, “some plastics are as tough as metal”
(s)bad, toughfeeling physical discomfort or pain (`tough' is occasionally used colloquially for `bad')“my throat feels bad”, “she felt bad all over”, “he was feeling tough after a restless night”
(s)baffling, elusive, knotty, problematic, problematical, toughmaking great mental demands; hard to comprehend or solve or believe“a baffling problem”, “I faced the knotty problem of what to have for breakfast”, “a problematic situation at home”