constant

Etymology

From Middle English constant, from Old French constant, from Latin constantem, accusative of constans, from constare (“to stand firm”). Displaced native Old English singal.

adj

1. Unchanged through time or space; permanent.
2. Consistently recurring over time; persistent.
   The constant pinging of electronic devices is driving many people to the end of their tether. Electronic devices not only overload the senses and invade leisure time. They feed on themselves: the more people tweet the more they are rewarded with followers and retweets. 2013-11-16, Schumpeter, “The mindfulness business”, in The Economist, volume 409, number 8862
3. Steady in purpose, action, feeling, etc.
4. Firm; solid; not fluid.
5. (obsolete) Consistent; logical.
6. (computing, complexity theory) Bounded above by a constant.
   constant time   constant space

noun

1. That which is permanent or invariable.
2. (algebra) A quantity that remains at a fixed value throughout a given discussion.
3. (sciences) Any property of an experiment, determined numerically, that does not change under given circumstances.
4. (computing) An identifier that is bound to an invariant value; a fixed value given a name to aid in readability of source code.