haphazard, hit-or-miss, stochastic, unselected, Randon, nonrandom, arbitrary, pseudorandom, quasirandom, oddball, more...

structured, deliberate, planned, systematic, intentional

random number, random sample, random variable, random walk, random process, random matrix, random graph, random forest, random walk model, more...

more, less, simple, pseudo, stratified, non, uniform, independent, sequential, systematic, longer

not chosen,   not determined,   not even; variable,   no pattern,   without pattern,   without a pattern,   no rhyme or reason,   happening by chance,   half hazard,   having no pattern