When I say "X" you think of all your experiences with "X" and I think of all of mine - these are not often the same, and may be even thought of as a Venn diagram.
The dimensions of the Venn diagram can vary greatly too, in fact an unknowable amount. Guessing at the range of commonalities you have with an acquaintance can only lead to anxiety:
If we are to assume the diagram's middle section is "great" then we are at risk of making ourselves a fool, but we are also very open. This though can also lead to great misunderstandings or interpreted rambling as one cannot be both professional and personable. One could easily be a fool when diving into a conversation that either your partner knows more of the details and interactions wherein your interpretation becomes basic.
If we are to assume the diagram's middle section is "slight" then we are assuming that common life experiences and languages are foreign and alien. Too much of this mindset might lead to withdrawal and even a feeling of fear of the unknown. One must remember to try to draw similarities, not differences with one another. One must try to connect, not be passive in our lives and force others to try to connect with us. This ultimately would make one unapproachable and judgmental.
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One should try to be innocent when speaking, but as direct as possible. Practice forgiveness of you and partners shared arguments, but also unafraid to argue. Don't you have to have a discussion to clarify understanding anyway? One should very actively try to understand language, bias, and practice active listening. Consider and uncover your similarities and don't attempt to define the relationship further than your conversation. Being purposely dense is great humor, but it has its place!
An ideal lifetime companion or significant other (SO) would have great conversation skills. As you spend time together, talking and interacting, your partner's personal language will become clearer to you. Their bias' and internal definitions will be applicable to more than one concrete idea in both of your shared lives. Mutual understanding is strengthened not through gravitas, but over time and wider application. Words rarely have height, only width. Words only gain weight by increased exposure to a partner or perceived gravitas.