- saccule
- sagittal
- sagittal suture
- Sainte Luce
- sakaizambohitra
- Sakalava
- salaka
- saline
- sambirano domain
- savannah
- scapula
- Scatterplot
- scavenger
- scorpions
- scrub
- sebaceous
- Secondary contact
- segment
- sekoly
- septate
- sericeous
- serology
- serrate
- seta
- sex
- sexual dichromatism
- sexual dimorphism
- Shape
- sheath
- Sibling species
- Sihanaka
- silk
- silt
- sinuate
- sinus
- sisal
- Sister group
- skeleton
- Skewness
- snakes
- soil
- somatic
- southern domain
- spatulate
- Species
- sperm
- sphenoid
- spheroidal
- spine
- spiny desert
- squamosal
- Standard deviation
- Statistical significance
- Stemminess
- steppe
- sternum
- stink fight
- stipe
- stock
- stomach
- styliform
- sub-
- sub-Recent
- subadult
- subfossil
- subgenus
- subhorizontal
- sublingua
- subspecies
- substrate
- sudoriparous
- sulcate
- sulcus
- supraoccipital
- suture
- swamp
- symbiosis
- sympatric
- Sympatric speciation
- sympatric species
- symphysis
- Symplesiomorphy
- Synapomorphy
- synonym
- Syntype
- systematics