top-heavy (adj.)

"highest point," Old English top "summit, crest, tuft," from Proto-Germanic *toppa- (source also of Old Norse toppr "tuft of hair," Old Frisian top "tuft," Old Dutch topp, Dutch top, Old High German zopf "end, tip, tuft of hair," German Zopf "tuft of hair"); no certain connections outside Germanic except a few Romanic words probably borrowed from Germanic.

Few Indo-European languages have a word so generic, which can be used of the upper part or surface of just about anything. More typical is German, which has Spitze for sharp peaks (mountains), oberfläche for the upper surface of flat things (such as a table). The meaning "highest position" is from 1620s; the meaning "best part" is from 1660s. The sense of "dominant sexual partner" is by 1961.

To go over the top is World War I slang for "start an attack," in reference to the top of the trenches; as "beyond reasonable limits, too far" it is recorded from 1968. Top of the world as "position of greatest eminence" is from 1670s. Top-of-the-line (adj.) is by 1950.

Old English hefig "heavy, having much weight; important, grave; oppressive; slow, dull," from Proto-Germanic *hafiga "containing something; having weight" (source also of Old Saxon, Old High German hebig, Old Norse hofugr, Middle Dutch hevich, Dutch hevig), from PIE root *kap- "to grasp." Jazz slang sense of "profound, serious" is from 1937 but would have been comprehensible to an Anglo-Saxon. Heavy industry recorded from 1932. Heavy metal attested by 1839 in chemistry; in nautical jargon from at least 1744 in sense "large-caliber guns on a ship."

While we undervalue the nicely-balanced weight of broadsides which have lately been brought forward with all the grave precision of Cocker, we are well aware of the decided advantages of heavy metal. [United Services Journal, London, 1830]

As a type of rock music, from 1972. Most other Germanic languages use as their primary word for this their equivalent of Middle English swere, Old English swær "heavy, sad; oppressive, grievous; sluggish, inactive, weak" (but never in a physical sense; see serious); for example, Dutch zwaar, Old High German suari, German schwer. The English word died out in the Middle Ages.