An instance of drawing something into one's mouth by inhaling.
"The baby opened wide to suck on his mother's nipple."
In plain English: A suck is an informal term for a foolish person who makes bad decisions.
"The movie sucked, so we left the cinema early."
draw into the mouth by creating a practical vacuum in the mouth
"suck the poison from the place where the snake bit"
"suck on a straw"
"the baby sucked on the mother's breast"
provide sexual gratification through oral stimulation
"She decided to suck on his earlobe while he told her about their plans for the weekend."
To use the mouth and lips to pull in (a liquid, especially milk from the breast).
"The baby began to suck at his mother's breast immediately after being held skin-to-skin."
In plain English: To suck means to pull something into your mouth using your lips and tongue.
"The baby was sucking on her thumb while she waited for dinner."
Usage: Use this verb specifically when describing the physical action of drawing liquid into your mouth with suction. It is often paired with objects like a bottle or nipple but should not be used metaphorically for general failure unless clearly distinguished from other slang meanings.
The word "suck" comes from the Old English verb sūcan, which originally meant to draw liquid into the mouth. It traveled directly into Middle English and has retained its core meaning of sucking or nursing since Proto-Germanic times.