1. (adjective) having rugged physical strength; inured to fatigue or hardships

• hardy
• stalwart
• stout

2. (adjective) not making concessions

• inflexible
• uncompromising

3. (adjective) substantially made or constructed

• tough

1. (adjective) having rugged physical strength; inured to fatigue or hardships

• robust

2. (adjective) not making concessions

• hard-line
• hardline

3. (adjective) substantially made or constructed

• rugged

1. (adjective) not making concessions

• compromising
• conciliatory
• flexible

1. (adjective) having rugged physical strength; inured to fatigue or hardships

• hardiness
• lustiness
• robustness
• validity
• stalwartness
• stoutness
• sturdiness

2. (adjective) not making concessions

• inflexibility
• rigidity
• rigidness
• sturdiness

3. (adjective) substantially made or constructed

• sturdiness