Synonyms for Coincidentally:

adv

concurrently (adverb)
synergistically, unitedly, concurrently, cooperatively, synchronously, co-actively.
relationally (adverb)
Dependently, Adjunctly, relevantly, supplementally, Of, Connectedly, Concomitantly, analogously, germanely, attendantly.
simultaneously (adverb)
Concomitantly, contemporaneously, synchronously, concurrently, simultaneously.
together (adverb)
contemporaneously.
unitedly (adverb)
purely, coherently, Elementally, cohesively, unitedly, congruently, homogeneously, fundamentally, simply, holistically, integrally, Congruously, Atomically, Indivisibly, solidly, entirely, completely, singly.

adv.

all (adverb)
coincidently.
concurrently (adverb)
synergistically, cooperatively, co-actively, concurrently, synchronously.
jointly (adverb)
Connectedly, unitedly, concurrently, cooperatively, simultaneously, Concomitantly.
relationally (adverb)
Dependently, Adjunctly, relevantly, supplementally, Of, Connectedly, Concomitantly, analogously, germanely, attendantly.
simultaneously (adverb)
simultaneously, contemporaneously.
together (adverb)
contemporaneously.
unitedly (adverb)
purely, coherently, Elementally, cohesively, unitedly, congruently, homogeneously, fundamentally, simply, holistically, integrally, Congruously, Atomically, Indivisibly, solidly, entirely, completely, singly.

n.

fluke, incidental, accidentally, accident, coincidence, stochastic, time, serendipity, unlucky. coincidentally (noun)
coincidently.

Other synonyms:

unlucky, serendipity, accidentally, coincidence, fluke, stochastic. time. accident. Other relevant words:
coincidently, coincidence, accidentally, unlucky, fluke, serendipity, incidental, accident, time, stochastic.