Mixture and combination are the broadest of these terms, all of which suggest the bringing together of diverse elements into a new whole. While mixture may apply to any materials joined in any way, it is perhaps most appropriate for the adding together of amorphous quantities in which there is no surrendering of individual particles to a new identity: a mixture of sand and gravel; a mixture of fine tobacco; a mixture of peanuts and cashews. Metaphorically, it may suggest fortuitous collocations, as in a mixture of luck and perseverance; or it may imply a mingling of opposites, as in a mixture of good and bad. Combination suggests a closer union of mingled elements, though not necessarily their fusion: a combination of tested ingredients. Metaphorically, it can imply a conscious selection of elements for effect: a striking colour combination of blues and greys. It can also imply an eclectic distillation: a combination of several prevailing dramatic styles; new combinations of proven therapeutic techniques. It is more "high-toned" than mixture and is often used to confer status on the user.

Composite is more formal still than combination , but tends to imply that the materials have been patched or pieced together from disparate sources; in motion pictures, for example, a composite is a shot that consists of several superimposed images. The word can suggest a more complete fusion of elements: David Low’s Colonel Blimp was a composite of all those Was Office "brass hats" who pompously clung to antiquated ideas.

Blend suggests more fusion still and, generally, a loss of individual identity for the elements in a mixture : a blend of whiskies. The word suggests that skill, control and conscious intention governed the making of the new whole. While many kinds of material can be used in a blend , the word suggests most specifically a mixture of fluids or gases.

Alloy and amalgam in their most specific senses refer to new metals made by fusing two or more metals in order to obtain valuable properties of each in the new combination . Alloy is the generic term for any such blend, while amalgam is a specific term referring to an alloy of another metal with mercury. Metaphorically, amalgam is loosely used to mean combination , and here it most often suggests a confused combination : The child’s account of what happened was an amalgam of fact and fancy. Metaphorically, alloy is often used to suggest the mixture of a fine quality with a baser one that reduces its purity: an alloy of love and possessiveness.

Compound , in its scientific sense, indicates the closest unity of any of these words; it refers to a chemical formed from two or more elements. Water, for example, is a compound of hydrogen and oxygen. In metaphorical uses, compound is less exact, meaning any mixture of things in fairly close relation to each other: a compound of wit and intelligence.