Not usefully related: not associated in any way that is important or useful to the context being discussed: not materially applicable; having connections not applicable in the present situation.
Not at all related: totally unrelated, wholly unconnected, completely inapplicable.
Relating to, or having a theme (“subject”) or a topic.
Relating to a melodic subject.
Of or relating to a theme (“subdivision of the Byzantine empire”).
Of a word stem, ending in a vowel that appears in or otherwise influences the noun or verb's inflection.
A postage stamp that is part of a thematic collection.