WordNet sense 1 (under great stress):

strained

WordNet sense 2 (easily agitated):

nervous

WordNet sense 3 (being in a tense state):

edgy, high-strung, uptight

WordNet sense 4 (subjected to great tension; stretched tight):

taut

WordNet sense 5 (become stretched or tense or taught):

strain

WordNet sense 6 (become tense, nervous, or uneasy):

tense up