The (polite) Four Letter Word Game

lobo

kobo

bosk

https://en.oxforddictionaries.com/definition/us/bosk

skol

silk

(+1)

sike

www.finedictionary.com/Sike.html
https://en.oxforddictionaries.com/definition/sike

pise

spiv

www.finedictionary.com/spiv.html

http://dictionary.cambridge.org/dictionary/english/spiv
www.collinsdictionary.com/dictionary/english/spiv#spiv__9

imps

:smiling_imp: :imp: :smiling_imp:

pams

:clubs:s

www.finedictionary.com/pam.html

vamp

vape

vare

http://www.finedictionary.com/Vare.html

yare

:cruise_ship:

adry

http://www.finedictionary.com/Adry.html

dyad

[ab]

www.finedictionary.com/dyad.html

duad

duan

www.finedictionary.com/Duan.html

undy

duny

The-Century-Dictionary-duny screenshot:

Merriam-Webster-duny screenshot: