_r)

Pure rotational spectra of the rare isotopologues of the TiO radical (X$^{3}Delta_{r}$) in their natural abundance have been measured using millimeter/submillimeter-wave direct absorption and Fourier transform millimeter-wave (FTmmW) techniques. Between five and seven rotational transitions each of $^{46}$TiO (8.2 %), $^{47}$TiO (7.4 %), $^{49}$TiO (5.4 %), and $^{50}$TiO (5.2 %) have been recorded for all three spin components in the frequency ranges 62-64 GHz and 255-522 GHz. In the millimeter-wave data, the TiO isotopologues were created in the gas phase from titanium vapor, produced with a specialized Broida-type oven, and N$_2$O. In the FTmmW spectrometer, laser ablation was used as a titanium source. Titanium hyperfine structure has been fully resolved for both $^{47}$TiO and $^{49}$TiO, resulting in distinctive sextets ($^{47}$Ti: I = 5/2) and octets ($^{49}$Ti: I = 7/2) in the millimeter data. The data has been analyzed, and rotation, fine structure, and hyperfine parameters have been determined. These spectroscopic constants are consistent with the past optical data, but have higher precision. TiO has recently been observed in the circumstellar envelope of VY CMa