quasiperiodic
/ˌkweɪzʌɪpɪərɪˈɒdɪk/ /ˌkwɑːzipɪərɪˈɒdɪk/adjective
1Chiefly Science. Almost or approximately periodic.
2 Mathematics. Of a function: such that increasing the variable by a certain fixed amount multiplies the value of the function by a fixed function, or increases it additively by a fixed function.
3 Physics. Of a motion, oscillation, etc.: having two periods incommensurable in duration.
4 Crystallography and Mathematics. Of a pattern, crystal lattice, etc.: such that any element recurs elsewhere, but at irregular intervals.
Origin
Late 19th century; earliest use found in Francis Anstie (1833–1874), physician. From quasi- + periodic.