Medical and biological term for saliva; also used for sputum in clinical contexts. In everyday conversation, つば is more common.
唾液の分泌が減ると口が渇きやすくなる。
When saliva secretion decreases, the mouth tends to become dry.
Just seeing a lemon made my mouth water.
検査のために唾液を採取した。
Saliva was collected for testing.
唾液腺は一日に約1.5リットルの唾液を分泌する。
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'.