Hunger was the desire to eat, experienced when a lifeform needed nutritional sustenance. To be starving or famished was the sensation of extreme hunger; when prolonged this sensation lead to starvation, also known as famine.
When attempting to go through Borg space, Kathryn Janeway did not feel hungry even though she had allegedly not eaten in two days. (VOY: "Scorpion")
When The Doctor's program created a delusion that he was a Human, he stated that he was hungry. (VOY: "Projections").
After being rid of an alien influence that was possessing him, Miles O'Brien felt hungry, which Beverly Crusher thought was a good sign. (TNG: "Power Play")
Odo became hungry shortly after being turned into a Human. (DS9: "Broken Link")
When Hugh first arrived on the USS Enterprise-D, Beverly Crusher wondered if he was hungry, seeing as despite not eating exactly, Borg needed to absorb energy. (TNG: "I Borg")
When Neelix offered Lon Suder some leola root stew, Suder stated that he was not hungry, but Neelix put it aside in case Suder changed his mind. Later, Seska wondered if her son was hungry. (VOY: "Basics, Part I")
Jean-Luc Picard once noted to Samuel Clemens that by the 24th century, hunger was not a serious problem due to hungry people having easy access to food. (TNG: "Time's Arrow")
Due to being an android, Data was unable to become hungry. When he had amnesia on Barkon IV, he did not eat his soup due to said inability to be hungry. The Barkonians thought that this meant he was unwell, but Data replied that he was fine, he just had no desire to eat. (TNG: "Thine Own Self")
When Harry Kim was asked by the Doctor to narrate his dream to him after aliens were interfering with the dreams of the USS Voyager's crew, he felt awkward, because he had dreamt that Seven of Nine was kissing him and flirting with him, and she was present, so he used being hungry, which he likely actually was because he had not eaten in seventeen hours, as an excuse to get out of talking about the dream. (VOY: "Waking Moments")
When Tom Paris was arguing with B'Elanna Torres, Neelix offered him some food, but Tom was not hungry. (VOY: "Vis à Vis")
When John Torres offered his daughter B'Elanna some fish while camping when B'Elanna was a child, B'Elanna replied that she was not hungry. (VOY: "Lineage")
Working while hungry was not recommended. (VOY: "Scorpion", "Shattered")
Nygean law enforcement workers apparently liked to keep their prisoners hungry by only feeding them once a day. When the crew of Voyager was dealing with prisoners of a Nygean jail, Tom Paris and B'Elanna Torres were hungry and went to the mess hall to get some food. Neelix wanted to tell them about the status of the prisoners, but Lt. Paris was too hungry to be patient. (VOY: "Repentance")
When Cyrano Jones tried to defend the genetically-engineered Tribbles, who were eating the Quadrotriticale that was required to feed a planet's population by saying that they were hungry, James T. Kirk replied that the planet's people were hungry too. (TAS: "More Tribbles, More Troubles")
William T. Riker generally disliked Klingon food, so when a Klingon observed that Riker did not finish his meal, Riker stated that he was not very hungry. (TNG: "A Matter Of Honor")
James Kirk considered the ability to feel hungry and therefore eat to be a pleasurable experience that his android counterpart would never experience. However, the android believed that not experiencing hunger was an advantage because it made him unable to starve. (TOS: "What Are Little Girls Made Of?")
When Helen Johansson was testing a machine meant to change people's thoughts on James Kirk, she suggested that he was hungry. It succeeded in making him think he was hungry and he suggested they find and raid a kitchen. (TOS: "Dagger of the Mind")
Sometimes, sadness could hinder one's appetite (TNG: "Imaginary Friend"), but by no means always, and sometimes, people could even eat something they enjoyed to cheer themselves up. (TNG: "Deja Q"). The appetite could also be negatively affected by apprehension, an example being the time Jake Sisko was not hungry because he was concerned for Nog. (DS9: "The Nagus")
When Croden was hungry, Odo was surprised because Croden had recently killed somebody and it was unusual to feel hungry after doing something that immoral. Croden said that he was only hungry because Ro-Kel had died and both brothers worked as one organism. (DS9: "Vortex")
When aliens made the imaginings of the Deep Space 9 crew become real, the alien manifesting itself as Buck Bokai became hungry, which confused Kira Nerys because she had mistaken him for a hologram, which do not eat. (DS9: "If Wishes Were Horses")
When Quark made Sakonna a feast, he said that he hoped she was hungry, then declared that they would wait until after the feast to have their business negotiation because he himself was also hungry and one of the Rules of Acquisition was to never discuss business on an empty stomach. (DS9: "The Maquis, Part I")
When Tekeny Ghemor was trying to convince Major Kira that she was actually Iliana Ghemor, he offered her some hasperat, but she said that she was not hungry. (DS9: "Second Skin")
One of the first sentences spoken by a young Jem'Hadar was "I need food". (DS9: "The Abandoned")
Kira Nerys generally disliked food served at Quark's Bar, Grill, Gaming House and Holosuite Arcade, but she occasionally ate there if she was extremely hungry. (DS9: "Sons of Mogh", "Bar Association")
Due to suffering from the Blight, Norva thought she was going to die before Old age and saved some food for the time of her death. However, when she heard that Julian Bashir might have been able to cure it, she gave it to him and Jadzia Dax, who were very hungry at the time, in hopes that she would not require it. (DS9: "The Quickening")