The verb “shake” forms the present perfect tense with the auxiliary verb “have” and the past participle “have shaken”. I have shaken the rug already. They have shaken many hands today. The verb “shake” comes from Old English “sceacan,” which means to move to and fro, often rapidly.

The causes of random shaking without any reason are anxiety disorders, fatigue, anemia, sleeplessness, excess caffeine intake, medications like theophylline which is used to treat asthma, low blood sugar levels, and essential tremors which run in the family(cause is unknown). Certain health conditions like Parkinson's' disease, Hyperthyroidism, and liver disorder can also lead to shaky hands.

to become unsteady; totter. The basketball player suddenly shook and fell to the floor. to take the hand of another as in greeting or congratulations. In this country, it is common to shake when you are introduced to someone. to move (something) back and forth or up and down with rapid, jerky motions. Shake the bottle before you pour the medicine.

infml A shake is a milkshake. Just thinking about the upcoming interview gave him the shakes. Shareholders' hopes of a quick profit have been badly shaken by recent events. The credit crunch shook public confidence in the financial system. shake hands with sb He waited in the lobby to shake hands with prospective customers.