Relevant words for adjective optional

Below are synonyms, antonyms and words that are in some manner relevant to adjective optional (as applied to automotive subject domain). You may view concordance (full context) and matched context for essential words.

Relevance	Word	Links
100.00%	optional	Concordance - Matched context
40.01%	principal	Concordance - Matched context
39.52%	additional	Concordance - Matched context
35.94%	important	Concordance - Matched context
35.94%	essential	Concordance - Matched context
29.34%	operative	Concordance - Matched context
27.13%	necessary	Concordance - Matched context
26.40%	main	Concordance - Matched context
26.35%	conditioning	Concordance - Matched context
25.79%	auxiliary	Concordance - Matched context
24.88%	limiting	Concordance - Matched context
24.58%	key	Concordance - Matched context
22.94%	ancillary	Concordance - Matched context
22.79%	supplementary	Concordance - Matched context
22.12%	indispensable	Concordance - Matched context
21.66%	supplemental	Concordance - Matched context
20.98%	basic	Concordance - Matched context
19.68%	imperative
19.24%	subsidiary	Concordance - Matched context
18.28%	unnecessary	Concordance - Matched context
17.98%	major	Concordance - Matched context
17.80%	critical	Concordance - Matched context
14.79%	extra	Concordance - Matched context
14.08%	fundamental	Concordance - Matched context
13.09%	required hydraulic
13.03%	needless
13.02%	relevant	Concordance - Matched context
12.27%	significant	Concordance - Matched context
11.35%	main fuel metering
11.16%	complementary	Concordance - Matched context
11.14%	minor	Concordance - Matched context
9.41%	required	Concordance - Matched context
8.20%	nominal	Concordance - Matched context
7.98%	preferential	Concordance - Matched context
6.84%	pressing	Concordance - Matched context
5.93%	substantial	Concordance - Matched context
4.06%	predominant	Concordance - Matched context
2.33%	considerable	Concordance - Matched context
2.25%	slight	Concordance - Matched context
1.96%	leading	Concordance - Matched context