I thought I had left language barriers behind when I left South Africa. I thought it would be easy to talk about mission and Mthatha now that everyone (or most everyone) I would be talking to spoke English as a first language. Ha!
A few weeks back I spoke at diocesan convention. There was a sign language interpreter there and I later asked here what the sign for “mission” is. She showed me it and said it was the same sign for “work.”
I thanked her and walked away but I was horrified. All my time in South Africa I had realized that mission is not about work but about presence and relationship. I started using the phrase “mission being and doing” to capture this reality. (This phrase was picked up at a higher level in the church.)
And now deaf people were hearing me talk about my “work”! It’s enough to make me scream with frustration.
And then I remember that mission happens as much in the overcoming of barriers as it does once those barriers are overcome.
Jesse Zink 
I wonder if they could have used a word related to “serving” or “ministry”? Although that would imply that service is limited to missionaries.
I don’t see anything wrong with the word “work,” although it represents the “doing” part…you would have to add some qualifiers to represent the “being” part.
I see nothing wrong with missionaries describing themselves as “working” overseas, but they will have to be able to explain further, since the idea of work is fairly abstract.
As an afterthought, I would prefer “work” to “mission.” I would rather think of myself as living a normal life, while being devoted to Christ. With the word “mission,” people think of proselytism, imperialism, and all those other associations, which you have probably covered already. Of course, if they are Christians, they may think “saint,” which is even worse, because they make you out to be someone you’re not.