insatiable — not satiable; incapable of being satisfied or appeased: insatiable hunger for knowledge.
obtainable — to come into possession of; get, acquire, or procure, as through an effort or by a request: to obtain permission; to obtain a better income.
occasional — occurring or appearing at irregular or infrequent intervals; occurring now and then: an occasional headache.
persuadable — to prevail on (a person) to do something, as by advising or urging: We could not persuade him to wait.
replaceable — to assume the former role, position, or function of; substitute for (a person or thing): Electricity has replaced gas in lighting.
rotational — the act of rotating; a turning around as on an axis.
sensational — producing or designed to produce a startling effect, strong reaction, intense interest, etc., especially by exaggerated, superficial, or lurid elements: a sensational novel.
sustainable — capable of being supported or upheld, as by having its weight borne from below.
unbreakable — to smash, split, or divide into parts violently; reduce to pieces or fragments: He broke a vase.
unsalable — subject to or suitable for sale; readily sold: The books were sent back by the store in salable condition.
unshakable — to move or sway with short, quick, irregular vibratory movements.
computational — Computational means using computers.
confrontational — If you describe the way that someone behaves as confrontational, you are showing your disapproval of the fact that they are aggressive and likely to cause an argument or dispute.
conversational — Conversational means relating to, or similar to, casual and informal talk.
unobtainable — to come into possession of; get, acquire, or procure, as through an effort or by a request: to obtain permission; to obtain a better income.
Four-or-more syllable rhymes
biodegradable — Something that is biodegradable breaks down or decays naturally without any special scientific treatment, and can therefore be thrown away without causing pollution.
denominational — Denominational means relating to or organized by a particular religious denomination.
invitational — restricted to participants who have been invited: an invitational track meet.
motivational — the act or an instance of motivating, or providing with a reason to act in a certain way: I don't understand what her motivation was for quitting her job. Synonyms: motive, inspiration, inducement, cause, impetus.