By Galen. Ars medica. HMD Collection, MS E 78. - Courtesy of the National Library of Medicine. Images from the History of Medicine (IHM), http://ihm.nlm.nih.gov/images/A109089. Also showcased in the book: Hidden Treasure (New York, NY: Blast Books, 2012), p. 22., Public Domain, https://commons.wikimedia.org/w/index.php?curid=27433700
The phrase, learning a language, sometimes suggests learning something stable. However, language does change over time. This might be due to technological advances, and new concepts, where new words are needed for new things. Bus and telephone used to be new words. Bus in fact was occasionally spelt 'bus instead of bus, when it emerged in the nineteenth and early twentieth centuries, because it is a shortened form of omnibus, a Latin word, meaning for everybody.
Nouns can be turned into verbs too. This is an old habit, and it carries on today. To chair a meeting, meaning to preside over a meeting, comes from the nouns chairman and chair. You can make up new verbs from nouns at will, and people will often understand them. But the verbs need to be used for a while to get accepted into the language.
The noun, delivery, and the verb, to deliver mean formally handing over something to someone, such as a letter or a parcel. More and more in the twentieth century, deliver is used to mean providing something abstract, or intangible, such as a project or a lesson.
Where people used to say, in the future, or in time to come, they might use the phrase, going forward, instead.
Words for numbers, though, are very slow to change!
stable - not changing its position, firm, steady. I could also have used the word, static, here, meaning standing still
intangible - something which cannot be touched
abstract - an idea, quality or state rather than a solid object. You can have abstract nouns and concrete nouns. An example of an abstract noun is redness; an example of a concrete noun is apple, because an apple exists as a physical object.