Abarim Publications' online Biblical Greek Dictionary
There are two words of the identical form τις (tis), and although in post-Biblical times these words became accented slightly different, in Biblical times they were indistinguishable, and had to be identified from their contexts. This doesn't always work out so smoothly, and although their meanings are really quite similar, this adds width to the compass of the Scriptures — much to the excitement of some, and much to the chagrin of others.
The particle τις I (tis I) is an enclitic indefinite pronoun, which means that it is rather unstressed in a sentence and points at something vague: "one", as in "someone" or "one of those" or "some or other". When it comes with a numeral it means roughly/approximately (roughly so many). It may mean some as in "some days" and on occasion it denotes a specific few from an indistinct some: some-two (Luke 7:19, Acts 23:23).
Our particle may also assume a more definite character when it's attached to a substantive: (some)one laughing, or one (certain) person, or even somewhat happy, in some measure or in some way somehow. It sometimes precedes εις (heis), meaning one, to form "some one" or "a certain person" and in the genitive case it may mean "one of (some group)". On rare occasions it may attain a similar emphasis as is expressed in the English "he is someone".
The particle τις II (tis II) is an interrogative pronoun and means who? which? what? and although dictionaries commonly devote column after column of flowery nuance, this word pretty much works straight forward and rather similar to who? which? what? in English. But, obviously, in Greek the grammatical cases may turn this word into mini-sentences: whose? or "what for?" "where from?"
If our word appears without a clear reference (what is that? or who is that?) the gender in which our word appears is usually sufficiently suggestive. But if our word is linked, even remotely, to objects with obvious gender (books, palm trees), this pronoun may appear as if asking for persons.
Our particle is often teamed up with other particles to form idiom, but also shows up in a few proper compounds:
- Truncated and together with the particle of negation μη (me), meaning no: the particle μητι (meti), meaning something like "isn't this the case?" or "aren't these the guys who...?" (Matthew 7:16, Luke 9:13, 2 Corinthians 1:17).
- Together with the nominative single form of the relative pronoun, namely ος (os), meaning "that/who/which": the indefinite relative pronoun οστις (hostis), meaning something like "whoever, whatever, anyone who" (Matthew 5:39, Luke 2:4, 1 Corinthians 5:1).