DAILY VOCABULARY WITH PICTURES. SIP.

• sip past tense and past participle sipped, present participle sipping [intransitive and transitive]
• to drink something slowly, taking very small mouthfuls:
• She was sitting at the table sipping her coffee.
• sip at
• He sipped at his wine with pleasure.

Definition from the Longman Dictionary of Contemporary English
Advanced Learner's Dictionary.

sip

source: thefreedictionary.com