Pend, stemming from the Latin verb pendere, meaning “hang,” is used exclusively in legal terminology, as a verb meaning “be awaiting,” but it appears as the root of many other words referring to hanging or weight, which are listed and defined in this post.
Something that is pending is waiting to be resolved. A pendant is a fixture or ornament that hangs; the word can also refer to a certain type of rope used in sailing, is a British English variant of pennant (a small, tapering flag), and may also refer to something complementary or supplementary, such as a companion volume to a book. A compendium (“weigh together”), meanwhile, is a collection; it is frequently used in a literary sense.
To append (“weigh out”) is to attach something, and something attached to something else, such as a limb, is often referred to as an appendage. Supplemental content attached to the end of a book is called an appendix, and a vestigial organ of the body is so named because it hangs from the large intestine. (Its full name is vermiform appendix; the first word means “wormlike”).
To depend (“hang from”) on someone or something is to rely on him, her, or it; the adjectival form is dependable, dependent is both an adjective and a noun, and dependence is the noun form. (Antonyms referring to freedom from reliance are independent and independence, while codependent, codependence, and codependency refer to control or manipulation of one person by another.)
To prepend (“weigh before”) is to consider. To expend (“weigh out”) is to pay; the adjectival form is expendable (though it can also be used as noun). Something impending (“hanging over”) is about to occur; the basic verb form is rare. A stipend (“weigh payment”) is money given as pay for short-term work, generally a modest amount not equivalent to a salary.
To suspend (“hang up”) is to hang something or cause someone to wait for something; the feeling that results is suspense, and the act is called suspension.
A pendulum is a weight that swings to and fro to regulate movement; it may also refer figuratively to movement from one position to its opposite. Something that swings heavily can be described as pendulous. Perpendicular (“hanging thoroughly”) means “projecting at right angles”); it is sometimes employed as a synonym for precipitous and may refers to individuals of distinctive types. (Perpendiculum is the Latin term for a plumb line, a weighted cord that in conjunction with gravity is used to ensure that an upright structural element is straight.) Pendentive is an architectural term for a structural element that helps support a dome.