muchness pushed to the limit: the quality of being abundant or forceful, used almost always to mean very or exceedingly
At its root מְאֹד names sheer quantity or force, the property of being a great deal of something. Hebrew puts that idea to work almost entirely as an intensifier: tacked onto a describing word or an action, it pushes the statement to its limit, so good becomes very good, heavy becomes extremely heavy, multiplied becomes multiplied beyond measure. This is the word's everyday job in roughly nine of every ten uses.
The more emphatic shades grow out of that same core. When the word is doubled, or stacked on a small word for in, it is the strongest dial Hebrew has for piling on degree: not merely very, but utterly, overwhelmingly so. The covenant blessings to Abraham and the swarming growth of Israel in Egypt use this stacked form to say the increase was past all reckoning.
Twice the word steps out as a thing in its own right rather than a degree word. In the command to love God with all your heart, life, and מְאֹד, and in the matching praise of King Josiah, it names the whole of a person's capacity: physical strength, will, and even property and possessions, the total much-ness one has to give. The breadth of that one word is exactly why translators and ancient interpreters reached for so many different terms for it.
Nuances
How to take the substantival מאד (your מאד) in the third clause of the Shema, love God with all your heart, life, and מאד.
- contestedStrength or capacity: personal vigor, power, or capacity (the might tradition).; S. R. Driver, A Critical and Exegetical Commentary on Deuteronomy (ICC, 1895), on 6:5; Septuagint (Old Greek), dynamis; cf. J. W. Wevers, Notes on the Greek Text of Deuteronomy (SBLSCS 39, 1995), pp. 115-116
- contestedProperty or possessions: one's wealth or material resources.; Targum Onkelos (Sperber, The Bible in Aramaic, Brill 1959), nikhsakh (your property); Mishnah Berakhot 9:5, be-khol mamonkha (with all your money)
- contestedDeliberately inclusive totality: the whole range of capacities (physical, mental, material) by which one loves God, refusing to narrow.; Moshe Weinfeld, Deuteronomy 1-11 (Anchor Bible 5, 1991), pp. 339, 351-352; Jeffrey H. Tigay, Deuteronomy (JPS Torah Commentary, 1996), p. 77; S. Dean McBride, The Yoke of the Kingdom, Interpretation 27 (1973): 273-306