The opposite could be strict (not lenient), or harsh (the reverse of lenient).
lenient,liberal
Lax or lenient.
stern
Yes.
"The teacher was very lenient with our grades on the last test.""His father is very lenient when it comes to punishment"The judge was lenient when handing down a sentence of 5 years in jail to the prisoner for murder"He was very strict about his students being promptly on time, but given the snowstorm that had left the campus under two feet of snow, he was very lenient with the students who showed up ten or fifteen minutes late that day".The judge was lenient when handing down a sentence of 5 years in jail to the prisoner for murder
lenient,liberal
lenient
strict
Lax or lenient.
The answer to the analogy "rigid is to flexible" is "strict is to lenient." Just as rigid and flexible are opposite in terms of stiffness, strict and lenient are opposite in terms of severity.
laxLax, gentle, loose, liberal are all opposites of strict.
The antonym of lenient is strict.
The judge's decision was lenient, she was only given a fine.
Lenient: adj.: To go easy on someone or something. To be patient, kind and gentle.
How about convenient
stern
A lenient sentence gives some leeway to the defendant and is less harsh than wanted or expected.