Medical and biological term for saliva; also used for sputum in clinical contexts. In everyday conversation, つば is more common.
Just seeing a lemon made my mouth water.
When saliva secretion decreases, the mouth tends to become dry.
Saliva was collected for testing.
The salivary glands secrete about 1.5 liters of saliva a day.
When you're nervous, saliva production drops and your mouth gets dry.
唾液 is the formal, medical term for saliva, while よだれ is the everyday word for drool that drips from the mouth.
Standard kanji spelling for the medical/biological term.
Kana spelling used in informal or explanatory contexts, or when the kanji are considered difficult.
From Middle Chinese 唾液 (tʰɑp̚ jiᴇiH, 'saliva'). The kanji 唾 means 'saliva' and 液 means 'fluid'.