Princeton's WordNet

1. aboard, on board(adverb)

   on a ship, train, plane or other vehicle

2. aboard, on base(adverb)

   on first or second or third base

   "Their second homer with Bob Allison aboard"

3. aboard, alongside(adverb)

   side by side

   "anchored close aboard another ship"

4. aboard(adverb)

   part of a group

   "Bill's been aboard for three years now"

Kernerman English Learner's Dictionary

1. aboard(preposition)əˈbɔrd, əˈboʊrd

   on or onto a vehicle

   Welcome aboard flight 5412.; Welcome aboard!

Wiktionary

1. aboard(Adverb)

   On board; into or within a ship or boat; hence, into or within a railway car.

   We all climbed aboard.

2. aboard(Adverb)

   Alongside

   The ships came close aboard to pass messages.

3. aboard(Adverb)

   On base.

   He doubled with two men aboard, scoring them both.

4. aboard(Adverb)

   Astride; with one leg on each side.

5. aboard(Preposition)

   On board of; as, to go aboard a ship.

   We all went aboard the ship.

6. aboard(Preposition)

   Across; athwart.

   Nor iron bands aboard The Pontic Sea by their huge navy cast. - Edmund Spenser

Origin: * First attested from late 14th century.

Webster Dictionary

1. Aboard(adverb)

   on board; into or within a ship or boat; hence, into or within a railway car

2. Aboard(adverb)

   alongside; as, close aboard

3. Aboard(u)

   on board of; as, to go aboard a ship

4. Aboard(u)

   across; athwart

• aan boordAfrikaans
• عَلَى ظَهْرArabic
• на бордаBulgarian
• a bordoPortuguese (BR)
• an BordGerman
• om bordDanish
• πάνω σε (μεταφορικό μέσο), επιβιβασμένοςGreek
• a bordo (de)Spanish
• peal, peale, pardal(e)Estonian
• سوار بر؛ در عرشهFarsi
• junassa, junaan; bussissa, lentokoneessa jne.Finnish
• à bord (de)French
• עַל כּלִי רֶכֶבHebrew
• सवारHindi
• ukrcanCroatian
• (hajóra stb.) száll, beszállHungarian
• di atasIndonesian
• um borðIcelandic
• a bordoItalian
• ～に乗ってJapanese
• (배 등을) 타고Korean
• į (lėktuvą/laivą/traukinį ir pan.)arba verčiamas atitinkamų daiktavardžių vietininkuLithuanian
• uz kuģa (vilcienā, lidmašīnā, autobusā)Latvian
• menaikiMalay
• aan boordDutch
• om bordNorwegian
• w, naPolish
• سوار برPersian
• سپاره ، سپرلىPashto
• a bordoPortuguese
• la bordRomanian
• на борт; в поездRussian
• na palubu, do vlaku (ap.), na palube, vo vlakuSlovak
• na krov(u)Slovenian
• uSerbian
• ombordSwedish
• บนยานพาหนะThai
• (gemi, uçak, tren, otobüs)e..., -deTurkish
• 在(某種交通工具上)上Chinese (Trad.)
• на судні; у вагоні; на бортуUkrainian
• جہاز، کستی یا کسی سواری پر سوارUrdu
• ở trênVietnamese
• 在（船、车、飞机）上Chinese (Simp.)