adj. 1
False, especially of money; intended to deceive or carry appearance of being genuine.
This counterfeit watch looks like the real thing, but it broke a week after I bought it.
v. 1
To falsely produce what appears to be official or valid; to produce a forged copy of.
to counterfeit the signature of another, coins, notes, etc.
v. 2
Of a turn or river card, to invalidate a player's hand by making a better hand on the board.
n. 1
A non-genuine article; a fake.

Forms

Plural: counterfeits → forgeries, imitations, pirates…
Past participle: counterfeited
e.g. counterfeited → faked, forged, copied, falsified…

Example sentences

Use in printed books, per decade from 1850 to 2019.

2 letters: do¹
3 letters: bad¹, act¹, ape¹
4 letters: base¹, copy², fake¹, coin¹, mock¹, sham¹
5 letters: cheat¹, forge¹, mimic², bogus², phony², fudge¹, feign¹
6 letters: assume², pirate², forged¹, pseudo², phoney²
7 letters: assumed², pretend², bastard², imitate³, forgery³, feigned¹, falsify³, fictive
8 letters: simulate³, spurious³
9 letters: synthetic³, pretended³, simulated⁴, imitation⁴, imitative⁴, dissemble³
10 letters: artificial⁴, fraudulent³, fictitious³
11 letters: unauthentic⁴
12 letters: illegitimate⁵

The small number after each word is its number of syllables (copy² = 2 syllables).