A tagset is a list of part-of-speech tags (POS tags for short), i.e. labels used to indicate the part of speech and sometimes also other grammatical categories (case, tense etc.) of each token in a text corpus.

Universal POS tags are part-of-speech marks used in Universal Dependencies (UD) which is a project that is developing cross-linguistically consistent treebank annotation for many languages. The annotation scheme is based on an evolution of (universal) Stanford dependencies (de Marneffe et al., 2006, 2008, 2014), Google universal part-of-speech tags (Petrov et al., 2012), and the Interset interlingua for morphosyntactic tagsets (Zeman, 2008). This page lists part-of-speech tags for the 2nd version of Universal Dependencies.

This is the 2nd version POS tagset of Universal Dependencies.

An Example of a tag in the CQL concordance search box[tag="NOUN"] finds all nouns (note: please make sure that you use straight double quotation marks)

Tagset

POS tag Description
ADJ  adjective
ADP  adposition
ADV  adverb
AUX  auxiliary
CCONJ  coordinating conjunction
DET  determiner
INTJ  interjection
NOUN  noun
NUM  numeral
PART  particle
PRON  pronoun
PROPN  proper noun
PUNCT  punctuation
SCONJ  subordinating conjunction
SYM  symbol
VERB  verb
X  other

Source: http://universaldependencies.org/u/pos/index.html