The origin band in the electronic transition to the dipole bound excited state of C(5)H(D)(-) anions was measured using two-color photodetachment spectroscopy. The rotational analysis of the partially resolved contour is consistent with a linear structure of the anion in both the ground X(3)Σ(-) and excited A(3)Π electronic states, in contrast with an earlier interpretation. The following spectroscopic constants are inferred for C(5)H(-): T(00) = 19248.0(1), B' = 0.0835(1), B'' = 0.0826(2), A'(SO) = -11.96(1), λ(SS)' = 1.97(8) λ(SS)'' = 0.24(15). Ab initio calculations at the UHF-MP2 level support the conclusion that C(5)H(-) is linear in the ground state. The experimentally determined ground state rotational constant can be used in the search for the millimeter wave spectrum of C(5)H(-).