The coverage dependent orientation of CO adsorbed on a Cu(110) surface was studied by the electron-stimulated desorption ion angular distribution (ESDIAD) technique. A neutral excited (CO*) species is imaged and in addition positive ions are measured. The adsorption temperature was varied between 32 K and 150 K. By applying the ESDIAD technique at a temperature below 80 K it was possible to decrease the beamwidths drastically, to determine the angular distributions better than +/-0.5 degrees, and to study the adsorption of CO chemisorbed and physisorbed on the surface. With increasing CO coverage we observe three distinct ESDIAD patterns, Starting from a normal beam pattern with an elliptical cross section with the major axis oriented in the [1 (1) over bar 0] direction for coverages up to 0.2 monolayer (ML), a transformation of the ESDIAD pattern into a pattern of two separated beams is observed for a coverage of about 0.5 ML, indicating a tilting of the molecules in the [1 (1) over bar 0] directions by similar to 9 degrees. With further increasing CO coverage an additional central peak develops with an elliptical broadening now in the [001] direction. The changes of the pattern are reversible as shown by decreasing the coverage by thermal desorption. Based on these ESDIAD and digital low energy electron diffraction results, a linear-chain model for CO adsorption is proposed. Temperature programmed desorption measurements also indicate the presence of repulsive CO-CO interactions in the adlayer.