moreover (adv.)

Old English mara "greater, relatively greater, more, stronger, mightier," used as a comparative of micel "great" (see mickle), from Proto-Germanic *maiz (source also of Old Saxon mera, Old Norse meiri, Old Frisian mara, Middle Dutch mere, Old High German meriro, German mehr, Gothic maiza), from PIE *meis- (source also of Avestan mazja "greater," Old Irish mor "great," Welsh mawr "great," Greek -moros "great," Oscan mais "more"), perhaps from a root *me- "big."

Sometimes used as an adverb in Old English ("in addition"), but Old English generally used related ma "more" as adverb and noun. This became Middle English mo, but more in this sense began to predominate in later Middle English.

"Take some more tea," the March Hare said to Alice, very earnestly.

"I've had nothing yet," Alice replied in an offended tone, "so I can't take more."

"You mean you can't take less," said the Hatter: "it's very easy to take more than nothing."

As a noun, "a greater quantity, amount, or number," in Old English. More and more "larger and larger amounts" is from 12c. More or less "in a greater or lesser degree" is from early 13c.; appended to a statement to indicate nearness but not precision, from 1580s. The more the merrier "the larger the company the greater the enjoyment" is from late 14c. (þe mo þe myryer).

Old English ofer "beyond; above, in place or position higher than; upon; in; across, past; more than; on high," from Proto-Germanic *uberi (source also of Old Saxon obar, Old Frisian over, Old Norse yfir, Old High German ubar, German über, Gothic ufar "over, above"), from PIE root *uper "over."

As an adjective from Old English uffera. The senses of "past, done,  finished; through the whole extent, from beginning to end" are attested from late 14c. The sense of "so as to cover the whole surface" is from c. 1400. Meaning "leaning forward and down" is from 1540s. The meaning "recovered from" is from 1929. In radio communication, it is used to indicate the speaker has finished speaking (1926).

Above expresses greater elevation, but not necessarily in or near a perpendicular direction; over expresses perpendicularity or something near it: thus, one cloud may be above another, without being over it. Over often implies motion or extension where above would not; hence the difference in sense of the flying of a bird over or above a house, the hanging of a branch over or above a wall. In such uses over seems to represent greater nearness. [Century Dictionary]

Phrase over and above (mid-15c.) is pleonastic, for emphasis. Adjective phrase over-the-counter is attested from 1875, originally of stocks and shares. To be (someone) all over "be exactly what one expects of (someone)" is by 1721.