Here's what rhymes with acknowledgement.

Consider these alternatives

affirmation / information implicit / visit belated / related apology / quality acquiescence / presence recognition / position repudiation / operation approbation / operation denunciation / relation renunciation / relation apologies / qualities allusion / conclusion denial / trial intimation / information reaffirmation / information uncritical / critical distaste / based reiteration / education contrition / position gratitude / food explicit / visit clarification / education rebuff / enough rebuke / puke hesitation / information nod / not signified / side disdain / main unspoken / broken