synchronicitous

Etymology

 * . Attested since the late 20th century.

Adjective

 * 1) Of or pertaining to synchronicity;  demonstrating synchronicity or apparent synchronicity.

Usage notes
Whereas the noun corresponds to the adjective, and the noun  corresponds to the adjective , a dedicated adjective to correspond with the noun  could not well be either  or , because those words already had other well-established senses. The next natural back-formation candidate after those words was (analogous to /), and it is therefore unsurprising that that adjective is long since attested.