The Chinese word for mustard is
芥末

jiè mò

Chinese Definition

mustard
1. 芥末
Components
芥
1. mustard greens (Brassica juncea)
2. (literary) small grass
3. (literary, figurative) triviality
末
1. tip; treetop
末梢 - tip; end
2. (by extension) effect; result
本末 - cause and effect
3. late or the last stage; conclusion; close
(ant, zh, 首, 初, 始)
月末 - month-end
明末清初 - late-Ming and early-Qing era
文末提到 - Toward the end of the article, it was mentioned…
4. final; the last; concluding; closing; terminal
(ant, zh, 首, 初, 始)
末代 - the last (in one's lineage)
末日 - doomsday; apocalypse
末法時期 - Dharma-ending age
5. insignificant; trivial; inferior; low-priority; low-class
捨本逐末 - pursuing the unimportant while neglecting the essential
6. powder; fine particulate matter
粉末 - powder
7. (literary, dated) not; none; no (negative indicator)
Synonyms: 未, 莫, 無
8. (mo) (a category of male roles in traditional Chinese theatre and opera)
9. (Same as) 麼.
10. (Used to mark a conditional subordinate clause.)
要是儂一家頭拿勿到末，叫個人來幫忙。 - tr=2iau zr&3non&4iq ka deu&3nau veq tau meq&2jiau hheq&3nyin&3le&1paan maan, If you can’t carry it on your own, ask for someone to help., SH
儂勿去蘇州末，要告訴我一聲。 - tr=3non&5veq qi&1su tseu meq&2iau+2kau su&3ngu&4iq san, If you're not going to Suzhou, let me know., ref=2007, Qian Nairong, 上海话大词典, page 309, SH
11. (Used to mark the topic in a topic-comment construction.)
新衣裳末，我已經買了兩件。 - tr=1xi i zaan meq&3ngu&2i jin&3ma leq&3lian ji, ref=2007, Qian Nairong, 上海话大词典, page 309, As for the new clothes, I've already bought two of them., SH