S to Saint Lawrence River

Saint Lawrence Seaway to Sambucus nigra

Same-sex marriage to Santa Maria de Belém

Santalaceae to Saturday

Saturn to Scarlet pimpernel

Scarlet Tanager to Scottish Deerhound

Scottish Terrier to Sea snake

Sea spider to Selection

Selene to Serine

Serinus to Shale

Shallot to Ship

Ship canal to Shumard Oak

Shutdown to Silesia

Silhouette to Sino-Tibetan languages

Sinusoidal projection to Skylab

Skylark to Smallpox

Smalltooth sawfish to Snorkeling

Snout to Sodium thiopental

Sodium thiosulfate to Something

Somme River to South Vietnam

South West Africa to Sparrow

Sparta to Spikenard

Spikes to Spotted Hyena

Spotted Owl to Stage Door

Stage Left to Steam locomotive

Steam shovel to Stick figure

Stickball to Strait of Magellan

Strait of Messina to Struthiomimus

Strychnine to Sulfacetamide

Sulfadiazine to Supertanker

Supply-side economics to Sweater

Sweatpants to Syzygium