| ruthless(adjective, mean, severe, harsh, cruel) |
| set(adjective, tough, severe, firm, harsh) |
| severe(adjective, mean, tough, firm, harsh) |
| square(adjective, tough, severe, firm, harsh) |
| steady(adjective, persistent, constant, pitiless, unyielding) |
| stern(adjective, tough, severe, firm, harsh) |
| stickling(adjective, tough, severe, firm, harsh) |
| stiff(adjective, severe, harsh, rigid, tight) |
| stiff-necked(adjective, persistent, constant, pitiless, unyielding) |
| straight(adjective, tough, severe, firm, harsh) |
| stringent(adjective, tough, severe, firm, harsh) |
| tenacious(adjective, persistent, constant, pitiless, unyielding) |
| unabated(adjective, persistent, constant, pitiless, unyielding) |
| unappeasable(adjective, mean, severe, harsh, cruel) |
| unbending(adjective, persistent, constant, pitiless, unyielding) |
| unbroken(adjective, persistent, constant, pitiless, unyielding) |
| uncalled-for(adjective, mean, severe, harsh, cruel) |
| unfeeling(adjective, mean, severe, harsh, cruel) |
| unflinching(adjective, mean, severe, harsh, cruel) |
| unforgiving(adjective, mean, severe, harsh, cruel) |