Coolant mass flow rate per open flow area, measured in $\mathrm{kg}{\mathrm{m}}^{-2}{\mathrm{s}}^{-1}$. A decrease in total flow does not establish a decrease in mass flux when the open area also changes.

Dynamic topography is surface or internal-boundary relief supported by stresses from interior flow. Inferring it requires separating effects of the thickness of the crust, thermal subsidence and other loads, and depends on the assumed interior viscosity and density structure.

A main-sequence star is a star powered predominantly by sustained hydrogen burning in its core. Hydrostatic equilibrium balances gravity with a pressure gradient, while thermal equilibrium approximately balances the nuclear energy supply with losses. The Sun is an example; a red dwarf is a cooler, lower-mass example.

Membership in the main sequence describes an evolutionary state, rather than simply small size or low luminosity. A white dwarf can be hotter and smaller while lacking sustained core hydrogen burning. Within the main sequence, a steep mass-luminosity relation makes massive stars consume their accessible fuel faster, so a larger fuel supply does not necessarily give a longer main-sequence lifetime.

Coupling in which a magnetic material's preferred strain transfers mechanical stress to a piezoelectric constituent, producing an electrical response. It depends on interfaces, elastic load sharing and electrical boundary conditions; a composite's measured voltage is not by itself an intrinsic single-phase magnetoelectric coefficient.

Magnetization measured after cooling in an applied field, which can select magnetic domains or bias blocked moments.

Magnetization measured after cooling without an applied field and then applying a measuring field. Comparison with field-cooled magnetization probes history dependence and slow relaxation.

For a lattice spin system, magnetization density often means longitudinal spin per site, $⟨S_{\mathrm{tot}}^z⟩/N$. A magnetic moment per physical volume instead includes the gyromagnetic conversion and lattice-site number density. The convention should be specified when comparing a spin-chain result with SI magnetization.

Correlations that extend over a finite local distance without establishing macroscopic long-range order.

The spin-only magnetic moment neglects orbital contributions and approximates $g$ by two: ${\mu }_{\mathrm{eff}}=g\sqrt{S(S+1)}{\mu }_B=\sqrt{n(n+2)}{\mu }_B$ for $n$ parallel unpaired electrons. Four unpaired electrons give $\sqrt{24}{\mu }_B\simeq 4.90{\mu }_B$.

The energy of a magnetic dipole in an external field is $E=-\mathbf{\mu }\cdot \mathbf{B}$. For dimensionless angular-momentum projection $m$ and ${\mu }_z=-g{\mu }_{B}m$, the energy is $g{\mu }_{B}Bm$.

In the small-sphere oscillatory-field limit, surface current density excludes the changing magnetic field. Adding a central magnetic dipole to a uniform applied field and imposing zero normal field at the sphere gives $\mathbf{m}=-2\pi a^3{\mathbf{H}}_{\mathrm{inc}}$. The minus sign expresses diamagnetism; it does not make this dipole's backward radiation cancel the electric contribution.^[ref]

For a uniformly charged spherical shell rotating rigidly in the quasistatic nonrelativistic model, a latitude strip carries current $dI=\sigma \omega a^2\sin \theta d\theta$. Its loop area is $\pi a^2{\sin }^2\theta$, so integration uses ${\int }_0^{\pi }{\sin }^3\theta d\theta =4/3$ and gives $\mathbf{m}=Q{a}^2\mathbf{\omega }/3$. For an isolated conducting shell, $Q=4\pi {ϵ}_{0}aV$. Clockwise and counterclockwise descriptions require a viewing direction; the vector formula fixes the sign without that ambiguity.

With energy convention $E=-\mathbf{\mu }\cdot \mathbf{B}$, the difference of physical moments is the negative derivative of a transition energy. Some trapping conventions instead call the positive energy slope an effective magnetic moment. The sign convention must be stated; either gives the same absolute sensitivity of transition frequency to a field fluctuation.