High-spin states in138 Nd were investigated using the reaction 94 Zr( 48 Ca,4n), detecting coincident γ-rays with the gasp spectrometer. A rich level scheme was constructed including 4 bands of negative parity at low spins, 8 bands of dipole transitions and 8 bands of quadrupole transitions at medium spins. The Cranked Shell Model and the Tilted Axis Cranking model are used to assign configurations to the observed bands, where zero pairing is assumed. For selected configurations the case of finite pairing is also considered. A consistent notation for configuration assignment is introduced, which applies both for zero and finite pairing. The observed bands are interpreted as rotation around the short and long principal axes (quadrupole bands), as well as around a tilted axis (dipole bands). The dipole bands have an intermediate character, between magnetic and collective electric rotation. A pair of dipole bands are candidates for chiral partners, the first case this property has been identified in an even-even nucleus. The possible existence of the wobbling mode at low deformation and medium spins is discussed. The consistent interpretation of the multitude of observed bands strongly supports the existence of stable triaxial deformation at medium spins in 138 Nd.