only

adjective

1. Alone in a category.

   “He is the only doctor for miles.”

2. Singularly superior; the best.

3. Without sibling; without a sibling of the same gender.

   “He is their only son, in fact, an only child.”

4. Mere.

adverb

1. Without others or anything further; exclusively.

   “My heart is hers, and hers only.”

2. No more than; just.

   “The cat only sat on the mat. It didn't scratch it.”

3. As recently as.

   “He left only moments ago.”

4. Emphasizing something that is just or necessary.

   “It's only fair to let him borrow your kite, after you've had his toys all day.”

conjunction

1. Introduces a clause with negative polarity, often one which upsets the listener's expectations. Under the condition that; but. (clarification of this definition is needed)

   “You're welcome to borrow my bicycle, only please take care of it.”

2. Under the condition that; but. (clarification of this definition is needed)

   “You're welcome to borrow my bicycle, only please take care of it.”

3. But, except; but in fact. (clarification of this definition is needed)

   “I would enjoy running, only I have this broken leg.”

noun

1. An only child.

particle

1. Placed at the end of a sentence to emphasize that something is trivial, small, undemanding or deserving of belittlement.

   “Just need to replace the filter only.”