Uajiren - Steven Collins

Ubbi Dubbi - Unknown

UberLingua - Jonathan Hayward

Uchunata - Marcus Miles

Udraþ - Drydic_Guy

Uhli - Sean Hendricks

Ukhik - Pablo Flores

Ukunida - Jordan Lavender

Ummo

Ungil - Dean Easton

UNI - E. Wainscott

Unideo - Cattelain Eric

Uni Mar - J Harness

Unipix - Cindy Drolet

Unish - Language Research Institute, Sejong University

Unitario - M. Pleyer

Universal - G. I. Muravkin and L. I. Vasilevskij

Universala Lingva Kodo - Linxiang Wang

Universal Character - Cave Beck

Universal Cipher Language - Charles Stewart

Universalglot - Jean Pirro

Universal Networking Language

Universal Translation Language

Un'ky'ok - Jordan Lavender

Unnamed Conlang - Don P. Blaheta

Unstränng - Scott 'Blade' Hamilton

Üqoi - Bruce V. Bracken

Uropi - Joël Landais

Utésalañé - Jordan Lavender

Uusisuom - Daniel Tammet

uuteib eafeis - David Caveney