What do spaCy's part-of-speech and dependency tags mean?
<p>spaCy tags up each of the <code>Token</code>s in a <code>Document</code> with a part of speech (in two different formats, one stored in the <code>pos</code> and <code>pos_</code> properties of the <code>Token</code> and the other stored in the <code>tag</code> and <code>tag_</code> properties) and a syntactic dependency to its <code>.head</code> token (stored in the <code>dep</code> and <code>dep_</code> properties).</p>

<p>Some of these tags are self-explanatory, even to somebody like me without a linguistics background:</p>

<pre><code>&gt;&gt;&gt; import spacy
&gt;&gt;&gt; en_nlp = spacy.load('en')
&gt;&gt;&gt; document = en_nlp("I shot a man in Reno just to watch him die.")
&gt;&gt;&gt; document[1]
shot
&gt;&gt;&gt; document[1].pos_
'VERB'
</code></pre>

<p>Others... are not:</p>

<pre><code>&gt;&gt;&gt; document[1].tag_
'VBD'
&gt;&gt;&gt; document[2].pos_
'DET'
&gt;&gt;&gt; document[3].dep_
'dobj'
</code></pre>

<p>Worse, the <a href="https://spacy.io/docs/" rel="noreferrer">official docs</a> don't contain even a list of the possible tags for most of these properties, nor the meanings of any of them. They sometimes mention what tokenization standard they use, but these claims aren't currently entirely accurate and on top of that the standards are tricky to track down.</p>

<p>What are the possible values of the <code>tag_</code>, <code>pos_</code>, and <code>dep_</code> properties, and what do they mean?</p>