1. Marked by firm determination or resolution; not shakable
   "unwavering loyalty"
   - firm, steadfast, steady, stiff, unbendable, unfaltering, unshakable, unshakeable 
2. Not showing abrupt variations
   - level

See also: resolute, steady, unwaveringly

• family Secotiaceae
• family Selaginellaceae
• family Sepiidae
• family Septobasidiaceae
• family Serranidae
• family Sialidae
• family Sillaginidae
• family Siluridae
• family Simaroubaceae
• family Simuliidae
• family Sirenidae
• family Sisyridae
• family Sittidae
• family Solanaceae
• family Soleidae
• family Solenidae
• family Soricidae
• family Spalacidae
• family Sparganiaceae
• family Sparidae
• family Sphaeriaceae
• family Sphaerobolaceae
• family Sphaerocarpaceae
• family Sphecidae
• family Spheniscidae