| disciplined(adjective, severe) |
| exhausting(adjective, hard, tough, severe, rough) |
| faultless(noun, exact, precise, accurate) |
| flawless(adjective, right, perfect, exact, proper) |
| flinty(adjective, strong, hard, tough, severe) |
| hidebound(adjective, severe, obstinate, stubborn, unbending) |
| icy(adjective, severe) |
| immutable(adjective, hard, resolute, rigid, inflexible) |
| intemperate(adjective, hard, tough, severe, rough) |
| ironclad |
| mathematical(adjective, truth) |
| narrow |
| on the button(noun, expression, idiom, correct, right) |
| on the money(noun, expression, idiom, correct, right) |
| prudish(adjective, tough, severe, firm, harsh) |
| religious(adjective, thoughtful, sober, cautious, prudent) |
| resolute(adjective, hard, intense, rigid, inflexible) |
| steely(adjective, set, strong, hard, tough) |
| strait-laced(adjective, tough, severe, firm, harsh) |
| strenuous(adjective, hard, tough, severe, rough) |