newest
adj.the most recent or latest version of something. You use this to talk about the thing that was made or bought most recently.
adj.the superlative form of 'new', indicating the most recent in origin, discovery, or arrival.
“This is the newest phone on the market.”
“The newest member of our team joined just yesterday and is already helping with the project.”
“The museum's newest acquisition is a rare landscape painting that had been held in a private collection for over a century.”
As a superlative adjective, it is almost always preceded by the definite article 'the' or a possessive pronoun.
Do not use 'most' with adjectives that already have an '-est' ending.
From Middle English newest, from Old English nīwost, from Proto-Germanic niwistaz, from Proto-Indo-European néwisth₂os, superlative of néwos/néwyos (whence new). Cognate with Scots newest, Dutch nieuwst, German neueste, neuste, Icelandic nýjastur, Gothic 𐌽𐌹𐌿𐌾𐌹𐍃𐍄𐍃 (niujists), Ashkun nustári (“before”), Kamkata-viri nüštë́ř (“before”), Waigali nüst (“before”), Vedic Sanskrit नविष्ठ (náviṣṭha).
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.