Definition of "collimated"

Low-mass objects have much more collimated flows than high mass sources.

1984, Charles J. Lada, “Energetic Outflows, Winds and Jets around Young Stars”, in M. F. Kessler, J. P. Phillips, editors, Galactic and Extragalactic Infrared Spectroscopy, page 266

Wolf-Rayet stars are also argued9 to give rise to gamma-ray bursts, a related but rare class of explosions characterized by highly-collimated relativistic jets.

2008 May, A. M. Soderberg, et al., An extremely luminous X-ray outburst at the birth of a supernova, Accepted draft, page 3

Although the most collimated outflows look very much jet-like at the highest velocities, their behavior is much more classical at lower speeds.

2011, R. Bachiller, M. Tafalla, “Bipolar Molecular Outflows”, in Charles J. Lada, N.D. Kylafis, editors, The Origin of Stars and Planetary Systems, page 240

Closing the aperture results in more collimated light, as only light traveling in the right direction can make it through the smaller opening.

2012, Kurt Demaagd, Anthony Oliver, Nathan Oostendorp, Katherine Scott, Practical Computer Vision with SimpleCV: The Simple Way to Make Technology See, page 222