Most scientist outfits comprise of a traditional lab coat and grant a +5 bonus to Science.
The scientist outfit has a generic "lab gear look" and is found on various non-player characters in the Capital Wasteland. This outfit is worn by a ghoul scientist at SatCom Array NW-05a, Janice Kaplinski, Sandra Kundanika of The Pitt and by three or four Project Purity scientists.
In Fallout: New Vegas, Fantastic and Ignacio Rivas at HELIOS One both wear this outfit, as does Calamity in Jacobstown, Dr. Hildern at Camp McCarran and Chris Haversam at the REPCONN Test Site. The easiest way to get it without failing any quests or lowering reputation is by reverse pick-pocketing armor with a higher DT such as leather armor.
Lab technician outfit
The easiest way to obtain it would be from Anna Holt in Rivet City's Science Lab. Two other non-player characters in there are also wearing it, but they are marked as essential non-player characters and are thus unkillable.
Enclave scientist outfit
The Enclave scientist outfit has a similar look to the radiation suit, but is white with an orange-tinted Plexiglas helmet. It is worn only by Enclave scientists, who do not respawn. Therefore, there are only so many of them. Use other scientist outfits to repair them.
Several Enclave camp locations may spawn a scientist with this armor.
All-purpose science suit
The all-purpose science suit is identical in all but name with the Enclave scientist outfit. The suit was originally cut from Fallout 3, but was added into Fallout: New Vegas with patch 188.8.131.52x and can be found in the Followers of the Apocalypse safehouse.
Lab coat (Broken Steel)