(intransitive) To tremble or shake. / (intransitive, figuratively) To be in a state of fear, shock, amazement, etc., such as might cause one to tremble.

The sound made by a duck.

To make a noise like a duck. / (intransitive) Of a queen bee: to make a high-pitched sound during certain stages of development.

(derogatory) A fraudulent healer, especially a bombastic peddler in worthless treatments, a doctor who makes false diagnoses for monetary benefit, or an untrained or poorly trained doctor who uses fraudulent credentials to attract patients

To practice or commit quackery (fraudulent medicine). / (obsolete) To make vain and loud pretensions.

Falsely presented as having medicinal powers.

Being four times as long, as big or as many of something.

(transitive) To multiply by four. / (intransitive) To increase by a factor of four. / (rail transport) To provide four parallel running lines on a given stretch of railway.

Something that is four times the usual number, amount, size, etc. / (skating) A figure-skating jump with four revolutions in the air.

(obsolete) Of a person: cunning, crafty. / (obsolete) Cleverly made; artfully contrived. / (now dialectal) Strange or odd; unusual.