Definition of "trend"

trend¹

/tɹɛnd/

noun
plural trends
1. An inclination in a particular direction.
  Quotations
  Nevertheless, it is clear that the global energy demand for air-conditioning will grow substantially as nations become more affluent, […] . This trend will put additional strain not only on global energy resources but also on the environmental prospects of a warming planet.
  2013 September-October, Michael Sivak, “Will AC Put a Chill on the Global Energy Supply?”, in American Scientist
2. A tendency.
3. A fad or fashion style.
  Quotations
  To stay on top of what's happening, a good photographer has to follow the trends by watching what's being done in fashion magazines.
  2006, Michael Grecco, Lighting and the Dramatic Portrait, Amphoto Books, page 114
  But musical ancestry aside, the influence to which Bieber is most beholden is the current trends in pop music, which means Believe is loaded up with EDM accouterments, seeking a comfortable middle ground where Bieber’s impressively refined pop-R&B croon can rub up on techno blasts and garish dubstep drops (and occasionally grind on some AutoTune, not necessarily because it needs it, but because a certain amount of robo-voice is expected these days).
  2012 June 26, Genevieve Koski, “Music: Reviews: Justin Bieber: Believe”, in The Onion AV Club
4. (mathematics) A line drawn on a graph that approximates the trend of a number of disparate points.
5. (nautical) The lower end of the shank of an anchor, being the same distance on the shank from the throat that the arm measures from the throat to the bill.
6. (nautical) The angle made by the line of a vessel's keel and the direction of the anchor cable, when she is swinging at anchor.
verb
third-person singular simple present trends, present participle trending, simple past and past participle trended
1. (intransitive) To have a particular direction; to run; to stretch; to tend.
  Quotations
  Huntsman starts out with a vision of Theron that’s specific, unique, and weighted in character, but it trends throughout toward generic fantasy tropes and black-and-white morality, and climaxes in a thoroughly familiar face-off.
  2012 May 31, Tasha Robinson, “Film: Review: Snow White And The Huntsman”, in AV Club‎
2. (transitive) To cause to turn; to bend.
  Quotations
  Not farre beneath i' the Valley as ſhe trends / Her ſiluer ſtreame, ſome VVood-nymphs and her friends / That follovv'd to her aide, beholding hovv / The Brooke came gliding, […]
  1616, William Browne, “The Third Song”, in Britannia’s Pastorals. The Second Booke, London: […] Iohn Haviland, published 1625, page 110
3. (social media, intransitive, informal) To be the subject of a trend; to be currently popular, relevant or interesting.
  Quotations
  The hashtag #RepublicofThailand trended on Twitter in Thailand on Friday after parliament voted to push back the question of changing the constitution as protesters have demanded.
  2020 September 25, Reuters Staff, “Thai republican hashtag trends after constitution change delayed”, in Reuters‎, Reuters, retrieved 2020-09-25
  The platform, founded in 2006, also came along just as TV’s cultural cachet was rising, with a growth in ambitious, talk-about-able appointment series. “Mad Men” and “Breaking Bad” premiered during its run; twist-heavy serials like “Scandal” and “Game of Thrones” delivered the kind of OMG moments that got them trending regularly.
  2023 July 10, James Poniewozik, “The Twitter Watch Party Is Over”, in The New York Times‎

trend²

/tɹɛnd/

noun
uncountable
1. (UK, dialect, dated) Clean wool.
verb
third-person singular simple present trends, present participle trending, simple past and past participle trended
1. To cleanse or clean (something, usually wool).