Vödabuk

First-former

First parturition

First born

First birth

The first time

First-time

For the first time

First-born animal

Firstly

First-born son

First violin

Soprano

Single, sole, unique

Only, solely

Little oner (endearing term for a quantity or value of one, used for an object such as a coin, a die, or a playing card)

A million

A millionaire

A million's quantity

One-headed, monocephalous

Single-colored, single-coloured, monochrome, uni-coloured

One-eyedness

One-eyed person

One-eyed

One-legged (person or animal)

One-legged (object)

One-way (glass)

In one and the same way

Once

Once only

Onetime

One-handed

Singular (grammatical number, as opposed to plural)

Singular

At one go

Of one column, single-column

Balsam

To embalm

One kind of

Monolith

Simplicity

Simple

Simply, in a simple way

Naiveety, simple heartedness

Naive

Simplicity

To be simple

To simplify

Monovalency, univalence

Monovalent, univalent

For one voice