There are dictionaries in philosophy, but philosophy is somewhat involved in creating definitions, so there is nothing that serves as an authoritative dictionary for precisely defining philosophical terms, sorry. There are a range of resources that will help you to understand the original texts of philosophers, however. I'll start a list below.
What if I were to tell you there is no such thing as a perfectly adequate universal precising definition, and even if there were, you could get no one to agree on what they would be in the particular case?
In mathematics, the use of precising definitions in the axiomatic construction of mathematical theories is rather widespread because of the nature of mathematical propositions which are often characterized as synthetic a priori statements. The nature of mathematical propositions are so universal in their appeal to intuitions, that it leads some math philosophers to surmise that there is a reality accessible in some way to our mind where these ideas exist as objects, a view known as Platonism.
But it may be the truth that words created by philosophers are actually physical constructions of language. If that's the case, then to learn their meanings, you have to understand the context they are used in. And that context is not just linguistic context, but also context within their theory, and according to many European thinkers, context in the biographical, political, and historical contexts in which the words were produced, an idea in philosophical circles known as historicity. This perspective is particularly true of philosophy that isn't about numbers or objective phenomena such as biomolecules, but rather of ideas such as 'love', 'freedom', and 'meaning'.
What I'm saying is that there is not a handbook, something akin to the Handbook of Chemistry and Physics, that is a rather definitive guide. However, there are guides, anthologies, biographies, and encyclopedias that help you get perspective written by professional philosophers to provide that context to make things easier for you. If you're interested in Immanuel Kant, for instance, there are many Kant scholars who will explain Kant to you. So:
Encyclopedias: the Stanford Encyclopedia of Philosophy, the Internet Encyclopedia of Philosophy, and the Encyclopedia of Philosophy are three sets, the first two being available online and free, and the last found at many public libraries. Wikipedia also has articles organized (sort of) under its philosophy portal.
Guides: Blackwell Publishing puts out a series of companions, such as the Blackwell Companion to Metaphysics. Routledge also produces a series of guides to philosophy such as the Routledge Philosophy GuideBook to Kant and the Critique of Pure Reason.
Anthologies are helpful, such as A.J. Ayer's Logical Positivism, Richard Rorty's The Linguistic Turn, and so on. (My examples are biased towards my preferences to the analtyical tradition over the Continental one, which has many such anthologies also.)
Dictionaries also are good in a pinch too. Besides plain language dictionaries like Merriam-Webster and the vaunted OED, there are hard dictionaries like the Oxford Dictionary of Philosophy which has online and Kindle versions.
These are the sorts of references that will help you out. Lastly, it should be noted that in using language, it helps somewhat to know language. That might start with a good grammar of English, but also extend all of the way to a reading of the philosophy of language. Language has always been intertwined with philosophy, and both the ordinary language philosophers and other philosophers after the linguistic turn have advanced much philosophical theory regarding the relationship between language and philosophy, so at a minimum, it bears worth mentioning that a modicum linguistic knowledge might be beneficial in sorting out the deep mysteries of the universe and mere deepities.