The dielectric tunability of ferroelectric ceramics in the paraelectric phase is studied theoretically for the case where the dc bias electric field is orthogonal to the ac electric field of a signal. Results are obtained in the most general form and then applied to a treatment of Landau-Ginzburg-Devonshire-based models. Relationships are derived between the "transverse" (dc electric field is normal to the ac electric field) and "longitudinal" (dc and ac electric fields are parallel) tunabilities. The relevant available experimental data are discussed in the context of these results. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4774220]