1.  Unethical:  un means not, ethical means relating to moral principles. In other words, a person who lacks principles or morals. More like going against social or professional expectations of what right, immoral conduct                                                                          Sentences:                                                                                                       - It would be unethical to perform the experiment without the professors consent.                                                                                       - Lucy was resticated dues to her unethical practices during the examination.
2. Peevish: When you are easily irritated, cranky or grumpy you are said to be peevish. It can also include using a word, like a verbal filter(kind of having pet peeve).                                                                                       Sentences:                                                                                                    - harry is being peevish today which effect the whole room.                 - When rony's periods come she becomes peevish for 3 days.
3. Nefarious: When peoples actions are evil or wicked. nefas means “crime”.                                                                                                             Sentences:                                                                                                      - Politicians are nefarious, to be in power they use means which are corrupt and unethical.                                                                                     - there are many nefarious individuals on the internet who uses others personal information for monetary gains.
4. Persnickety: Its a fancy word for being fussy, more like picky about things.                                                                                                               Sentences:                                                                                                      - Mr. George is persnikety while checking the project due to which many students are likely to get less marks in Science.                             - Leon is being persnikety with the salad and will get us kicked out soon because of his ridiculous comments.
5. Supercilious: Act of being self-centered, thinking very highly of themselves. supercilium means haughty demeanor.                                Sentences:                                                                                                      - su lan's step sister and stepmother are supercilious about their positions in the company but little did they know that Su lan has higher shares than them.                                                                               - His spoke in a supercilious voice towards his dad.
6. Mendacious: Someone who tells lies everytime and does it intentionally.                                                                                                     Sentences:                                                                                                     - louis always said that he is my bestfriend but he was mendacious everytime and hurt me.                                                                                   - Meena told her sister some misleading and downright mendacious statements.
7. Irate: The final stage of anger is irate, like when tom is angry smoke comes out of his ears.                                                                                Sentences:                                                                                                      - His ill communication skills have made the boss irate of his way of dealing with things.                                                                                         - Tiana was irate when john was not near her during her surgery.
8. Contemptible: Who resecieve criticism, harsh judgement and also deserve it.                                                                                                         Sentences:                                                                                                       - His idealogy was marvellous but his portrail of idea is contemptible. - lara and george became comtemptible towards geography teacher so they both are more disobedient towards him.

--Please to let me know if any mistakes in the comment section. I hope you will get benefited with these words.