- sella turcica
- seller groove
- seminal receptacle
- seta
- somite
- spermatophore
- sternal groove
- sternal plastron
- sternite
- sterno-abdominal
- sternum
- subchela
- subhepatic region
- submedian carina
- submedian groove
- suborbital region
- suborbital spine
- supraorbital eave
- supraorbital spine
- suture
- swimming leg
- synovial membrane