It's a good thing that I stumbled upon this thread at random, because for some reason I did not get a notification that I had been mentioned, as I believe this website is set up to provide. Hmm.
Anyway, I don't know the particular dictionary reference mentioned in the OP, so I'm not sure if any response from me would be all that effective in countering whatever particular things the non-Trinitarian religions may teach about the Bible. I mean, I can guess (I've interacted with Mormons and JWs for years), but in terms of how any one particular sect makes use of the Bible, there are probably particular arguments that are better answered by those who know more about those particular heresies. I don't know what Christadelphians espouse in lieu of the Holy Trinity, for instance. (There aren't very many of them in the world to begin with, and I've never met one myself.)
That said, I don't believe that there is
anything out there that the Church has not encountered and effectively countered. So here are a few historical sources I would recommend to gain a basic knowledge of how the Church responded to the heresies of the non-Trinitarians when they arose the first time around, many centuries ago:
Against those who profess Arianism or semi-Arianism (the belief that the Father and the Son are of different essence/substance):
HH Pope St. Alexander of Alexandria (d. circa 328)
letter to Alexander of Constantinople
HH Pope St. Athanasius the Apostolic (d. 373; the successor to the above)
discourses against the Arians (audio book version, because the discourses taken together are quite a lot of material)
St. Ambrose of Milan (d. 397)
exposition of the Christian faith, book I
St. John Chrysostom (d. 407)
homily VI on Philippians
Against those who believe that the Holy Spirit is not divine/not consubstantial with the Father and the Son (Pneumatomachi, meaning 'Spirit-fighters', or Macedonianism):
St. Basil of Caesarea (d. 379)
on the Holy Spirit, and his
letter CXL to Antioch. The letter has only one explicit reference to the Pneumatomachi, but I want to call attention to it anyway because often times the anti-Trinitarians will point to the comparatively 'late' date at which the Church held its various councils to define the worship of the Holy Trinity against the ideas of heretics, as though this is itself some proof that the faith of our fathers is itself a 'late' invention (the implication being that the real/original/first Christians were in effect proto-Mormons, or proto-Iglesia Ni Cristo people, or whatever). Please take careful note of St. Basil's own explanation as to how the Creed was originally written at Nicaea without any such explicit affirmation of the Holy Spirit's divinity -- it is not because the Church believed Him not to be God (!), but quite simply because those who said that He is not God (the Pneumatomachi) had not yet arisen! The Arians and all other heretics can be considered similarly, which makes sense when you think about it (how can there be heresy if there is not an established belief to dissent from beforehand?).
Against those who adhere to any kind of Adoptionism (the belief that Jesus Christ was a human being who 'became' God by this or that means; I have seen some arguments that come very close to this from our Mormon friends on this very website, particularly as Mormonism teaches
'exaltation' whereby men become gods; I am not sure what other anti-Trinitarian groups might hold to something similar)
St. Hippolytus of Rome (d. 235)
Refutation of all heresies -- in particular, chapter 23 of book VI deals with Adoptionism, naming it the heresy of Theodotus, after its first known advocate.
These are not all the anti-Trinitarian heresies (nor anywhere near all the ancient sources that discuss them, of course), but most are types of what has already been covered here, so these should be good to read for a foundation. You can tell by reading the writings provided how intertwined all of these are with each other, and with other heretical groups I haven't mentioned (e.g., the Ebionites or other early Jewish Christian sects which accepted Christ as the Messiah but rejected His divinity; these obviously would not be Trinitarian, either). I have also purposely left out any explicit links to the acts or declarations of the councils and synods which countered all of these, since the list already contains several who were present at them (HH St. Alexander was at Nicaea with St. Athanasius his deacon as an aide, for instance), and those are generally full of declarative statements passing judgment on particular errant stances, rather than going into detail concerning how the Church had already arrived at the correct doctrine concerning all of these points.