to shake: to be thrown into violent, involuntary motion, whether the earth quaking, a person trembling, or an inward shuddering of dread, grief, or excitement
At its root this word names one thing: a violent shaking that comes over a body without its consent. The same word can describe mountains heaving, a nation's knees buckling in fear, a grieving father's whole frame convulsing, or the ground rocking in an earthquake. Hebrew lets that single picture of being shaken run all the way from the physical world into the human heart, so the senses below are not separate words but one shaking seen in different settings.
The setting usually tells you which shade is meant. When the subject is the created world (earth, mountains, the deep, the sky), it is a literal quaking, almost always at God's approach. When the subject is a crowd of people, it is terror. When the subject is one person, it is the bodily shudder of grief, dread, or eager anticipation. When God or a human agent is the one doing it to something else, the word turns causative: to make a thing shake, to rouse it up, or to provoke.
One further shade matters for readers of the New Testament. In later Hebrew, and especially in Aramaic, this word narrowed to mean plain anger, and that narrowing reached the ancient Greek translation of the Old Testament. So the call to tremble in Psalm 4:4 was rendered in Greek as be angry, which is the form the apostle Paul later quoted. In the Hebrew itself, though, anger is only a faint, late edge of a word whose heart is shaking, not rage.