Question: In karaniya metta sutta,

> 
> He who is skilled in (working out his own) well being, and who wishes to attain that state of Calm (Nibbana) should act thus: he should be dexterous, **upright**, **exceedingly upright**, obedient, gentle, and humble.
> 
> 
> 

What does it mean to be upright?

Answer: 
That's one of [several translations](https://suttacentral.net/kp9/) of this

> 
> Karaṇīyamatthakusalena,  
> 
> Yanta santaṃ padaṃ abhisamecca;  
> 
> Sakko ujū ca suhujū ca,  
> 
> Sūvaco cassa mudu anatimānī.
> 
> 
> 

They all translate it with the same word, "upright".

The Pali word are *ujū* (straight), *sakko* (able/capable), and *su-* (good).

Here is a dictionary definition: <https://suttacentral.net/define/uju>

The dictionary has cross-references to other suttas where it's used. Curiously the first of these is `DN.iii.150` i.e. [DN 30](https://suttacentral.net/dn30/en/sujato) where it seems to be used literally/physically -- e.g. a straight, well-formed body -- but there it's also used to describe eyes, behaviour, demeanour:

> 
> Mendicants, in some past lives the Realized One was reborn as a human being.
> When looking at others he didn’t glare, look askance, or avert his eyes. Being **straightforward**, he reached out to others with **straightforward** intentions, looking at people with kindly eyes.
> 
> 
>
> 
> araṇīyam'atthakusalena
> Yaŋ taŋ santaŋ padaŋ abhisamecca:
> ***Sakko** ujū* ca *sūjū* ca,
> Suvaco cassa mudu anatimānī.
> 
> 
> 

Practicing "respectfully, carefully, duly, thoroughly", very, very... more in [Karaṇīya Metta-Sutta](https://zugangzureinsicht.org/html/lib/authors/nanadassana/metta_en.html#cult)

(Upright is something only reached by stream enter, while metta to practice is open for worldlings as well.)